81678915904 has 56 divisors (see below), whose sum is σ = 172709265960. Its totient is φ = 38192234496.

The previous prime is 81678915869. The next prime is 81678915917. The reversal of 81678915904 is 40951987618.

It can be written as a sum of positive squares in 4 ways, for example, as 9360949504 + 72317966400 = 96752^2 + 268920^2 .

It is a hoax number, since the sum of its digits (58) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68269 + ... + 409900.

It is an arithmetic number, because the mean of its divisors is an integer number (3084094035).

Almost surely, 2^81678915904 is an apocalyptic number.

It is an amenable number.

81678915904 is an abundant number, since it is smaller than the sum of its proper divisors (91030350056).

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

81678915904 is a wasteful number, since it uses less digits than its factorization.

81678915904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 478355 (or 478345 counting only the distinct ones).

The product of its (nonzero) digits is 4354560, while the sum is 58.

The spelling of 81678915904 in words is "eighty-one billion, six hundred seventy-eight million, nine hundred fifteen thousand, nine hundred four".