81213252920 has 32 divisors (see below), whose sum is σ = 182740676400. Its totient is φ = 32483371008.

The previous prime is 81213252919. The next prime is 81213252949. The reversal of 81213252920 is 2925231218.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 758552 + ... + 858968.

Almost surely, 2^81213252920 is an apocalyptic number.

It is an amenable number.

81213252920 is an abundant number, since it is smaller than the sum of its proper divisors (101527423480).

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

81213252920 is a wasteful number, since it uses less digits than its factorization.

81213252920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120647 (or 120643 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 35.

The spelling of 81213252920 in words is "eighty-one billion, two hundred thirteen million, two hundred fifty-two thousand, nine hundred twenty".