31891887889 has 9 divisors (see below), whose sum is σ = 32212028667. Its totient is φ = 31574903064.

The previous prime is 31891887877. The next prime is 31891887913. The reversal of 31891887889 is 98878819813.

The square root of 31891887889 is 178583.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 17012767489 + 14879120400 = 130433^2 + 121980^2 .

It is not a de Polignac number, because 31891887889 - 2¹³ = 31891879697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31891887289) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 19107547 + ... + 19109215.

Almost surely, 2^31891887889 is an apocalyptic number.

31891887889 is the 178583-rd square number.

31891887889 is the 89292-nd centered octagonal number.

It is an amenable number.

31891887889 is a deficient number, since it is larger than the sum of its proper divisors (320140778).

31891887889 is an frugal number, since it uses more digits than its factorization.

31891887889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3552 (or 1776 counting only the distinct ones).

The product of its digits is 55738368, while the sum is 70.

The spelling of 31891887889 in words is "thirty-one billion, eight hundred ninety-one million, eight hundred eighty-seven thousand, eight hundred eighty-nine".