81131437851256 has 64 divisors (see below), whose sum is σ = 163952547655680. Its totient is φ = 37415696826240.

The previous prime is 81131437851229. The next prime is 81131437851287. The reversal of 81131437851256 is 65215873413118.

It is a junction number, because it is equal to n+sod(n) for n = 81131437851197 and 81131437851206.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1319458545 + ... + 1319520031.

It is an arithmetic number, because the mean of its divisors is an integer number (2561758557120).

Almost surely, 2^{81131437851256} is an apocalyptic number.

It is an amenable number.

81131437851256 is an abundant number, since it is smaller than the sum of its proper divisors (82821109804424).

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

81131437851256 is a wasteful number, since it uses less digits than its factorization.

81131437851256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71324 (or 71320 counting only the distinct ones).

The product of its digits is 4838400, while the sum is 55.

The spelling of 81131437851256 in words is "eighty-one trillion, one hundred thirty-one billion, four hundred thirty-seven million, eight hundred fifty-one thousand, two hundred fifty-six".