661

661
Basic Information
Cardinal Number	six hundred and sixty-one
Ordinal Number	six hundred and sixty first
Roman Numeral	DCLXI
Greek Numeral	ΧΞΑ´
Factorization	661
Different Representations
Binary Form	10100101012
Ternary Form	2201113
Quaternary Form	221114
Quinary Form	101215
Senary Form	30216
Septenary Form	16337
Octal Form	12258
Nonary Form	8149
Undecimal Form	55111
Duodecimal Form	47112
Tridecimal Form	3BB13
Quattuordecimal Form	35314
Quindecimal Form	2E115
Hexadecimal Form	29516
Septendecimal Form	24F17
Octodecimal Form	20D18
Novemdecimal Form	1FF19
Vigesimal Form	1D120
Unvigesimal Form	1AA21
Duovigesimal Form	18122
Trevigesimal Form	15H23
Quattuorvigesimal Form	13D24
Quinvigesimal Form	11B25
Hexavigesimal Form	PB26
Septenvigesimal Form	OD27
Octovigesimal Form	NH28
Novemvigesimal Form	MN29
Trigesimal Form	M130
Untrigesimal Form	LA31
Duotrigesimal Form	KL32
Tretrigesimal Form	K133
Quattuortrigesimal Form	JF34
Quintrigesimal Form	IV35
Hexatrigesimal Form	ID36
Previous	659
Current	661
Next	673

661 is a prime number from 601-700. 661 has 2 factors, 1 and 661. It is the 121st prime number, and the twelfth prime number from 601-700. 661 can be turned upside down to give 199, which is also a prime number. 

Proofs

• — 661 is divisible by 1.

• — 661 is not divisible by 2-660.

• — 661 is divisible by 661.

Relationship with other odd numbers

The numbers before

• The previous prime number is 659.
  • There are no odd numbers between 659 and 661. As a result, they are twin primes.
• The previous prime number before 659 is 653.

The numbers after

• The next prime number is 673.
  • Notably, 667 is the product of 23 and 29, while 671 is divisible by 11. They are both composite numbers.
• 677 is the next prime number after 673.

Trivia

• This prime number is nearest to "666" the number of Satan.

Prime Numbers 1-1,000