81556679137 has 8 divisors (see below), whose sum is σ = 81904474080. Its totient is φ = 81208962240.

The previous prime is 81556679123. The next prime is 81556679153. The reversal of 81556679137 is 73197665518.

It is a happy number.

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-81556679137 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81556679107) 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, 3182658 + ... + 3208180.

It is an arithmetic number, because the mean of its divisors is an integer number (10238059260).

Almost surely, 2^81556679137 is an apocalyptic number.

It is an amenable number.

81556679137 is a deficient number, since it is larger than the sum of its proper divisors (347794943).

81556679137 is a wasteful number, since it uses less digits than its factorization.

81556679137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39023.

The product of its digits is 9525600, while the sum is 58.

The spelling of 81556679137 in words is "eighty-one billion, five hundred fifty-six million, six hundred seventy-nine thousand, one hundred thirty-seven".