81977894867 has 16 divisors (see below), whose sum is σ = 90355288320. Its totient is φ = 73757704800.

The previous prime is 81977894857. The next prime is 81977894899. The reversal of 81977894867 is 76849877918.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81977894867 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81977894794 and 81977894803.

It is not an unprimeable number, because it can be changed into a prime (81977894807) 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 15 ways as a sum of consecutive naturals, for example, 461234 + ... + 613752.

It is an arithmetic number, because the mean of its divisors is an integer number (5647205520).

Almost surely, 2^81977894867 is an apocalyptic number.

81977894867 is a deficient number, since it is larger than the sum of its proper divisors (8377393453).

81977894867 is a wasteful number, since it uses less digits than its factorization.

81977894867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153034.

The product of its digits is 341397504, while the sum is 74.

The spelling of 81977894867 in words is "eighty-one billion, nine hundred seventy-seven million, eight hundred ninety-four thousand, eight hundred sixty-seven".