81178721364 has 48 divisors (see below), whose sum is σ = 207836399232. Its totient is φ = 24506781312.

The previous prime is 81178721321. The next prime is 81178721387. The reversal of 81178721364 is 46312787118.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4900944 + ... + 4917479.

It is an arithmetic number, because the mean of its divisors is an integer number (4329924984).

Almost surely, 2^81178721364 is an apocalyptic number.

It is an amenable number.

81178721364 is an abundant number, since it is smaller than the sum of its proper divisors (126657677868).

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

81178721364 is a wasteful number, since it uses less digits than its factorization.

81178721364 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9818496 (or 9818494 counting only the distinct ones).

The product of its digits is 451584, while the sum is 48.

The spelling of 81178721364 in words is "eighty-one billion, one hundred seventy-eight million, seven hundred twenty-one thousand, three hundred sixty-four".