31987878913 has 4 divisors (see below), whose sum is σ = 31989155908. Its totient is φ = 31986601920.

The previous prime is 31987878863. The next prime is 31987878917.

31987878913 is nontrivially palindromic in base 10.

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 17547771024 + 14440107889 = 132468^2 + 120167^2 .

It is a cyclic number.

It is not a de Polignac number, because 31987878913 - 2¹³ = 31987870721 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31987878917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 600156 + ... + 651277.

It is an arithmetic number, because the mean of its divisors is an integer number (7997288977).

Almost surely, 2^31987878913 is an apocalyptic number.

It is an amenable number.

31987878913 is a deficient number, since it is larger than the sum of its proper divisors (1276995).

31987878913 is a wasteful number, since it uses less digits than its factorization.

31987878913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1276994.

The product of its digits is 18289152, while the sum is 64.

The spelling of 31987878913 in words is "thirty-one billion, nine hundred eighty-seven million, eight hundred seventy-eight thousand, nine hundred thirteen".