31638540836 has 48 divisors (see below), whose sum is σ = 66186408960. Its totient is φ = 12938772000.

The previous prime is 31638540827. The next prime is 31638540839. The reversal of 31638540836 is 63804583613.

It is a Smith number, since the sum of its digits (47) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (31638540839) 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 15 ways as a sum of consecutive naturals, for example, 211211 + ... + 328461.

It is an arithmetic number, because the mean of its divisors is an integer number (1378883520).

Almost surely, 2^31638540836 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 31638540836, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33093204480).

31638540836 is an abundant number, since it is smaller than the sum of its proper divisors (34547868124).

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

31638540836 is a wasteful number, since it uses less digits than its factorization.

31638540836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117704 (or 117702 counting only the distinct ones).

The product of its (nonzero) digits is 1244160, while the sum is 47.

The spelling of 31638540836 in words is "thirty-one billion, six hundred thirty-eight million, five hundred forty thousand, eight hundred thirty-six".