81187825972 has 12 divisors (see below), whose sum is σ = 154994940576. Its totient is φ = 36903557240.

The previous prime is 81187825903. The next prime is 81187826021. The reversal of 81187825972 is 27952878118.

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, 922588888 + ... + 922588975.

It is an arithmetic number, because the mean of its divisors is an integer number (12916245048).

Almost surely, 2^81187825972 is an apocalyptic number.

It is an amenable number.

81187825972 is a deficient number, since it is larger than the sum of its proper divisors (73807114604).

81187825972 is a wasteful number, since it uses less digits than its factorization.

81187825972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1845177878 (or 1845177876 counting only the distinct ones).

The product of its digits is 4515840, while the sum is 58.

The spelling of 81187825972 in words is "eighty-one billion, one hundred eighty-seven million, eight hundred twenty-five thousand, nine hundred seventy-two".