81599401878 has 64 divisors (see below), whose sum is σ = 172581926400. Its totient is φ = 25649429760.

The previous prime is 81599401867. The next prime is 81599401883. The reversal of 81599401878 is 87810499518.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 37899250 + ... + 37901402.

It is an arithmetic number, because the mean of its divisors is an integer number (2696592600).

Almost surely, 2^81599401878 is an apocalyptic number.

81599401878 is an abundant number, since it is smaller than the sum of its proper divisors (90982524522).

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

81599401878 is a wasteful number, since it uses less digits than its factorization.

81599401878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3557.

The product of its (nonzero) digits is 5806080, while the sum is 60.

The spelling of 81599401878 in words is "eighty-one billion, five hundred ninety-nine million, four hundred one thousand, eight hundred seventy-eight".