31991065 has 8 divisors (see below), whose sum is σ = 39113928. Its totient is φ = 25109760.

The previous prime is 31991053. The next prime is 31991087. The reversal of 31991065 is 56019913.

It can be written as a sum of positive squares in 4 ways, for example, as 215296 + 31775769 = 464^2 + 5637^2 .

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

It is a de Polignac number, because none of the positive numbers 2^k-31991065 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31991065.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 60096 + ... + 60625.

It is an arithmetic number, because the mean of its divisors is an integer number (4889241).

Almost surely, 2^31991065 is an apocalyptic number.

It is an amenable number.

31991065 is a deficient number, since it is larger than the sum of its proper divisors (7122863).

31991065 is a wasteful number, since it uses less digits than its factorization.

31991065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 120779.

The product of its (nonzero) digits is 7290, while the sum is 34.

The square root of 31991065 is about 5656.0644444702. The cubic root of 31991065 is about 317.4506588339.

The spelling of 31991065 in words is "thirty-one million, nine hundred ninety-one thousand, sixty-five".