81136512 has 128 divisors (see below), whose sum is σ = 253735200. Its totient is φ = 25436160.

The previous prime is 81136511. The next prime is 81136537. The reversal of 81136512 is 21563118.

81136512 is a `hidden beast` number, since 8 + 1 + 1 + 3 + 651 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-2 number, since 2×81136512² = 13166267159052288, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81136511) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 58062 + ... + 59442.

Almost surely, 2^81136512 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81136512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (126867600).

81136512 is an abundant number, since it is smaller than the sum of its proper divisors (172598688).

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

81136512 is a wasteful number, since it uses less digits than its factorization.

81136512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1421 (or 1403 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 81136512 is about 9007.5808072978. The cubic root of 81136512 is about 432.9178017978.

The spelling of 81136512 in words is "eighty-one million, one hundred thirty-six thousand, five hundred twelve".