31697561 has 6 divisors (see below), whose sum is σ = 36872730. Its totient is φ = 27169296.

The previous prime is 31697557. The next prime is 31697569. The reversal of 31697561 is 16579613.

It can be written as a sum of positive squares in only one way, i.e., 31360000 + 337561 = 5600^2 + 581^2 .

It is not a de Polignac number, because 31697561 - 2² = 31697557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31697569) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 323396 + ... + 323493.

It is an arithmetic number, because the mean of its divisors is an integer number (6145455).

Almost surely, 2^31697561 is an apocalyptic number.

It is an amenable number.

31697561 is a deficient number, since it is larger than the sum of its proper divisors (5175169).

31697561 is an equidigital number, since it uses as much as digits as its factorization.

31697561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 646903 (or 646896 counting only the distinct ones).

The product of its digits is 34020, while the sum is 38.

The square root of 31697561 is about 5630.0587030687. The cubic root of 31697561 is about 316.4768510947.

The spelling of 31697561 in words is "thirty-one million, six hundred ninety-seven thousand, five hundred sixty-one".