31815880866 has 128 divisors (see below), whose sum is σ = 88418027520. Its totient is φ = 8238542400.

The previous prime is 31815880861. The next prime is 31815880879. The reversal of 31815880866 is 66808851813.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (31815880861) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1364740 + ... + 1387856.

It is an arithmetic number, because the mean of its divisors is an integer number (690765840).

Almost surely, 2^31815880866 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31815880866, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44209013760).

31815880866 is an abundant number, since it is smaller than the sum of its proper divisors (56602146654).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

31815880866 is a wasteful number, since it uses less digits than its factorization.

31815880866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23477 (or 23471 counting only the distinct ones).

The product of its (nonzero) digits is 2211840, while the sum is 54.

The spelling of 31815880866 in words is "thirty-one billion, eight hundred fifteen million, eight hundred eighty thousand, eight hundred sixty-six".