81131257057 has 8 divisors (see below), whose sum is σ = 84669235200. Its totient is φ = 77594156640.

The previous prime is 81131257033. The next prime is 81131257087. The reversal of 81131257057 is 75075213118.

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

It is a cyclic number.

It is not a de Polignac number, because 81131257057 - 2⁷ = 81131256929 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81131257087) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26932 + ... + 403717.

It is an arithmetic number, because the mean of its divisors is an integer number (10583654400).

Almost surely, 2^81131257057 is an apocalyptic number.

It is an amenable number.

81131257057 is a deficient number, since it is larger than the sum of its proper divisors (3537978143).

81131257057 is a wasteful number, since it uses less digits than its factorization.

81131257057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 438863.

The product of its (nonzero) digits is 58800, while the sum is 40.

The spelling of 81131257057 in words is "eighty-one billion, one hundred thirty-one million, two hundred fifty-seven thousand, fifty-seven".