31720985 has 8 divisors (see below), whose sum is σ = 38188680. Its totient is φ = 25294464.

The previous prime is 31720981. The next prime is 31720991. The reversal of 31720985 is 58902713.

It can be written as a sum of positive squares in 4 ways, for example, as 405769 + 31315216 = 637^2 + 5596^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 31720985 - 2² = 31720981 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (31720981) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8570 + ... + 11699.

It is an arithmetic number, because the mean of its divisors is an integer number (4773585).

Almost surely, 2^31720985 is an apocalyptic number.

It is an amenable number.

31720985 is a deficient number, since it is larger than the sum of its proper divisors (6467695).

31720985 is a wasteful number, since it uses less digits than its factorization.

31720985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20587.

The product of its (nonzero) digits is 15120, while the sum is 35.

The square root of 31720985 is about 5632.1385813916. The cubic root of 31720985 is about 316.5547890412.

The spelling of 31720985 in words is "thirty-one million, seven hundred twenty thousand, nine hundred eighty-five".