81671572956 has 12 divisors (see below), whose sum is σ = 190567003592. Its totient is φ = 27223857648.

The previous prime is 81671572943. The next prime is 81671572981. The reversal of 81671572956 is 65927517618.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 81671572896 and 81671572905.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3402982195 + ... + 3402982218.

Almost surely, 2^81671572956 is an apocalyptic number.

It is an amenable number.

81671572956 is an abundant number, since it is smaller than the sum of its proper divisors (108895430636).

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

81671572956 is a wasteful number, since it uses less digits than its factorization.

81671572956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6805964420 (or 6805964418 counting only the distinct ones).

The product of its digits is 6350400, while the sum is 57.

The spelling of 81671572956 in words is "eighty-one billion, six hundred seventy-one million, five hundred seventy-two thousand, nine hundred fifty-six".