81256318957 has 8 divisors (see below), whose sum is σ = 91699921440. Its totient is φ = 71322160560.

The previous prime is 81256318889. The next prime is 81256318961. The reversal of 81256318957 is 75981365218.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81256318957 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81256318898 and 81256318907.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81256318457) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 127360683 + ... + 127361320.

It is an arithmetic number, because the mean of its divisors is an integer number (11462490180).

Almost surely, 2^81256318957 is an apocalyptic number.

It is an amenable number.

81256318957 is a deficient number, since it is larger than the sum of its proper divisors (10443602483).

81256318957 is a wasteful number, since it uses less digits than its factorization.

81256318957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 254722043.

The product of its digits is 3628800, while the sum is 55.

The spelling of 81256318957 in words is "eighty-one billion, two hundred fifty-six million, three hundred eighteen thousand, nine hundred fifty-seven".