81951568216 has 48 divisors (see below), whose sum is σ = 180589235400. Its totient is φ = 34760001024.

The previous prime is 81951568207. The next prime is 81951568219. The reversal of 81951568216 is 61286515918.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81951568219) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1039606 + ... + 1115653.

Almost surely, 2^81951568216 is an apocalyptic number.

It is an amenable number.

81951568216 is an abundant number, since it is smaller than the sum of its proper divisors (98637667184).

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

81951568216 is a wasteful number, since it uses less digits than its factorization.

81951568216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2155376 (or 2155365 counting only the distinct ones).

The product of its digits is 1036800, while the sum is 52.

The spelling of 81951568216 in words is "eighty-one billion, nine hundred fifty-one million, five hundred sixty-eight thousand, two hundred sixteen".