31685985 has 28 divisors (see below), whose sum is σ = 57015252. Its totient is φ = 16897248.

The previous prime is 31685981. The next prime is 31686013. The reversal of 31685985 is 58958613.

It can be written as a sum of positive squares in 2 ways, for example, as 5645376 + 26040609 = 2376^2 + 5103^2 .

It is not a de Polignac number, because 31685985 - 2² = 31685981 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a nialpdrome in base 9.

It is a self number, because there is not a number n which added to its sum of digits gives 31685985.

It is not an unprimeable number, because it can be changed into a prime (31685981) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 702 + ... + 7991.

It is an arithmetic number, because the mean of its divisors is an integer number (2036259).

Almost surely, 2^31685985 is an apocalyptic number.

It is an amenable number.

31685985 is a deficient number, since it is larger than the sum of its proper divisors (25329267).

31685985 is an frugal number, since it uses more digits than its factorization.

31685985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8716 (or 8701 counting only the distinct ones).

The product of its digits is 259200, while the sum is 45.

The square root of 31685985 is about 5629.0305559661. The cubic root of 31685985 is about 316.4383204530.

The spelling of 31685985 in words is "thirty-one million, six hundred eighty-five thousand, nine hundred eighty-five".