81572739092 has 24 divisors (see below), whose sum is σ = 157308434976. Its totient is φ = 36773398368.

The previous prime is 81572739019. The next prime is 81572739107. The reversal of 81572739092 is 29093727518.

It is a happy number.

It is a super-2 number, since 2×81572739092² (a number of 23 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (53) coincides with the sum of the digits of its prime factors.

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, 18238538 + ... + 18243009.

It is an arithmetic number, because the mean of its divisors is an integer number (6554518124).

Almost surely, 2^81572739092 is an apocalyptic number.

It is an amenable number.

81572739092 is a deficient number, since it is larger than the sum of its proper divisors (75735695884).

81572739092 is a wasteful number, since it uses less digits than its factorization.

81572739092 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36481607 (or 36481605 counting only the distinct ones).

The product of its (nonzero) digits is 1905120, while the sum is 53.

The spelling of 81572739092 in words is "eighty-one billion, five hundred seventy-two million, seven hundred thirty-nine thousand, ninety-two".