665761331 has 2 divisors, whose sum is σ = 665761332. Its totient is φ = 665761330.

The previous prime is 665761319. The next prime is 665761351. The reversal of 665761331 is 133167566.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 665761331 - 2⁶ = 665761267 is a prime.

It is a super-2 number, since 2×665761331² = 886476299709783122, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (665761351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332880665 + 332880666.

It is an arithmetic number, because the mean of its divisors is an integer number (332880666).

Almost surely, 2^665761331 is an apocalyptic number.

665761331 is a deficient number, since it is larger than the sum of its proper divisors (1).

665761331 is an equidigital number, since it uses as much as digits as its factorization.

665761331 is an evil number, because the sum of its binary digits is even.

The product of its digits is 68040, while the sum is 38.

The square root of 665761331 is about 25802.3512688282. The cubic root of 665761331 is about 873.1848438211.

The spelling of 665761331 in words is "six hundred sixty-five million, seven hundred sixty-one thousand, three hundred thirty-one".