665902961 has 2 divisors, whose sum is σ = 665902962. Its totient is φ = 665902960.

The previous prime is 665902957. The next prime is 665902967. The reversal of 665902961 is 169209566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 343879936 + 322023025 = 18544^2 + 17945^2 .

It is a cyclic number.

It is not a de Polignac number, because 665902961 - 2² = 665902957 is a prime.

It is not a weakly prime, because it can be changed into another prime (665902967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332951480 + 332951481.

It is an arithmetic number, because the mean of its divisors is an integer number (332951481).

Almost surely, 2^665902961 is an apocalyptic number.

It is an amenable number.

665902961 is a deficient number, since it is larger than the sum of its proper divisors (1).

665902961 is an equidigital number, since it uses as much as digits as its factorization.

665902961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 174960, while the sum is 44.

The square root of 665902961 is about 25805.0956402025. The cubic root of 665902961 is about 873.2467581014.

The spelling of 665902961 in words is "six hundred sixty-five million, nine hundred two thousand, nine hundred sixty-one".