685631957 has 2 divisors, whose sum is σ = 685631958. Its totient is φ = 685631956.

The previous prime is 685631951. The next prime is 685631983. The reversal of 685631957 is 759136586.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 663268516 + 22363441 = 25754^2 + 4729^2 .

It is a cyclic number.

It is not a de Polignac number, because 685631957 - 2⁶ = 685631893 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685631951) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342815978 + 342815979.

It is an arithmetic number, because the mean of its divisors is an integer number (342815979).

Almost surely, 2^685631957 is an apocalyptic number.

It is an amenable number.

685631957 is a deficient number, since it is larger than the sum of its proper divisors (1).

685631957 is an equidigital number, since it uses as much as digits as its factorization.

685631957 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1360800, while the sum is 50.

The square root of 685631957 is about 26184.5747912774. The cubic root of 685631957 is about 881.7869838807.

The spelling of 685631957 in words is "six hundred eighty-five million, six hundred thirty-one thousand, nine hundred fifty-seven".