31865686561 has 4 divisors (see below), whose sum is σ = 31945953172. Its totient is φ = 31785419952.

The previous prime is 31865686549. The next prime is 31865686579. The reversal of 31865686561 is 16568656813.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 28677390336 + 3188296225 = 169344^2 + 56465^2 .

It is a cyclic number.

It is not a de Polignac number, because 31865686561 - 2¹⁷ = 31865555489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31865606561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40132710 + ... + 40133503.

It is an arithmetic number, because the mean of its divisors is an integer number (7986488293).

Almost surely, 2^31865686561 is an apocalyptic number.

It is an amenable number.

31865686561 is a deficient number, since it is larger than the sum of its proper divisors (80266611).

31865686561 is an equidigital number, since it uses as much as digits as its factorization.

31865686561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80266610.

The product of its digits is 6220800, while the sum is 55.

The spelling of 31865686561 in words is "thirty-one billion, eight hundred sixty-five million, six hundred eighty-six thousand, five hundred sixty-one".