31520725 has 6 divisors (see below), whose sum is σ = 39085730. Its totient is φ = 25216560.

The previous prime is 31520719. The next prime is 31520747. The reversal of 31520725 is 52702513.

It can be written as a sum of positive squares in 3 ways, for example, as 5541316 + 25979409 = 2354^2 + 5097^2 .

It is not a de Polignac number, because 31520725 - 2¹¹ = 31518677 is a prime.

It is a super-2 number, since 2×31520725² = 1987112209051250, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (25), and also a Moran number because the ratio is a prime number: 1260829 = 31520725 / (3 + 1 + 5 + 2 + 0 + 7 + 2 + 5).

It is a self number, because there is not a number n which added to its sum of digits gives 31520725.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 630390 + ... + 630439.

Almost surely, 2^31520725 is an apocalyptic number.

It is an amenable number.

31520725 is a deficient number, since it is larger than the sum of its proper divisors (7565005).

31520725 is a wasteful number, since it uses less digits than its factorization.

31520725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1260839 (or 1260834 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 25.

The square root of 31520725 is about 5614.3321063151. The cubic root of 31520725 is about 315.8872274245.

The spelling of 31520725 in words is "thirty-one million, five hundred twenty thousand, seven hundred twenty-five".