81915039956 has 12 divisors (see below), whose sum is σ = 144829169268. Its totient is φ = 40535277312.

The previous prime is 81915039953. The next prime is 81915039959. The reversal of 81915039956 is 65993051918.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81915039953) and next prime (81915039959).

It can be written as a sum of positive squares in 2 ways, for example, as 48099507856 + 33815532100 = 219316^2 + 183890^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81915039953) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 105560231 + ... + 105561006.

It is an arithmetic number, because the mean of its divisors is an integer number (12069097439).

Almost surely, 2^81915039956 is an apocalyptic number.

It is an amenable number.

81915039956 is a deficient number, since it is larger than the sum of its proper divisors (62914129312).

81915039956 is a wasteful number, since it uses less digits than its factorization.

81915039956 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211121338 (or 211121336 counting only the distinct ones).

The product of its (nonzero) digits is 2624400, while the sum is 56.

The spelling of 81915039956 in words is "eighty-one billion, nine hundred fifteen million, thirty-nine thousand, nine hundred fifty-six".