31887471921 has 16 divisors (see below), whose sum is σ = 42903135744. Its totient is φ = 21065151744.

The previous prime is 31887471907. The next prime is 31887471949. The reversal of 31887471921 is 12917478813.

It is not a de Polignac number, because 31887471921 - 2¹⁸ = 31887209777 is a prime.

It is not an unprimeable number, because it can be changed into a prime (31887421921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1875360 + ... + 1892286.

It is an arithmetic number, because the mean of its divisors is an integer number (2681445984).

Almost surely, 2^31887471921 is an apocalyptic number.

It is an amenable number.

31887471921 is a deficient number, since it is larger than the sum of its proper divisors (11015663823).

31887471921 is a wasteful number, since it uses less digits than its factorization.

31887471921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22600.

The product of its digits is 677376, while the sum is 51.

The spelling of 31887471921 in words is "thirty-one billion, eight hundred eighty-seven million, four hundred seventy-one thousand, nine hundred twenty-one".