690988957 has 2 divisors, whose sum is σ = 690988958. Its totient is φ = 690988956.

The previous prime is 690988933. The next prime is 690989009. The reversal of 690988957 is 759889096.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 668274201 + 22714756 = 25851^2 + 4766^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-690988957 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 690988895 and 690988904.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (690988927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345494478 + 345494479.

It is an arithmetic number, because the mean of its divisors is an integer number (345494479).

Almost surely, 2^690988957 is an apocalyptic number.

It is an amenable number.

690988957 is a deficient number, since it is larger than the sum of its proper divisors (1).

690988957 is an equidigital number, since it uses as much as digits as its factorization.

690988957 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9797760, while the sum is 61.

The square root of 690988957 is about 26286.6688075914. The cubic root of 690988957 is about 884.0775633539.

The spelling of 690988957 in words is "six hundred ninety million, nine hundred eighty-eight thousand, nine hundred fifty-seven".