81586778136 has 32 divisors (see below), whose sum is σ = 205455763440. Its totient is φ = 26997083648.

The previous prime is 81586778111. The next prime is 81586778153. The reversal of 81586778136 is 63187768518.

It is a super-2 number, since 2×81586778136² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81586778136.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12403461 + ... + 12410036.

Almost surely, 2^81586778136 is an apocalyptic number.

It is an amenable number.

81586778136 is an abundant number, since it is smaller than the sum of its proper divisors (123868985304).

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

81586778136 is a wasteful number, since it uses less digits than its factorization.

81586778136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24813643 (or 24813639 counting only the distinct ones).

The product of its digits is 13547520, while the sum is 60.

The spelling of 81586778136 in words is "eighty-one billion, five hundred eighty-six million, seven hundred seventy-eight thousand, one hundred thirty-six".