81913281152 has 32 divisors (see below), whose sum is σ = 164868976020. Its totient is φ = 40534401024.

The previous prime is 81913281127. The next prime is 81913281157. The reversal of 81913281152 is 25118231918.

It can be written as a sum of positive squares in 2 ways, for example, as 81901281856 + 11999296 = 286184^2 + 3464^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is not an unprimeable number, because it can be changed into a prime (81913281157) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3286283 + ... + 3311114.

Almost surely, 2^81913281152 is an apocalyptic number.

It is an amenable number.

81913281152 is an abundant number, since it is smaller than the sum of its proper divisors (82955694868).

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

81913281152 is an equidigital number, since it uses as much as digits as its factorization.

81913281152 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6597508 (or 6597496 counting only the distinct ones).

The product of its digits is 34560, while the sum is 41.

The spelling of 81913281152 in words is "eighty-one billion, nine hundred thirteen million, two hundred eighty-one thousand, one hundred fifty-two".