81137812 has 24 divisors (see below), whose sum is σ = 164235456. Its totient is φ = 34353408.

The previous prime is 81137807. The next prime is 81137827. The reversal of 81137812 is 21873118.

It is a happy number.

It is a super-2 number, since 2×81137812² = 13166689072294688, which contains 22 as substring.

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, 15133 + ... + 19780.

It is an arithmetic number, because the mean of its divisors is an integer number (6843144).

Almost surely, 2^81137812 is an apocalyptic number.

It is an amenable number.

81137812 is an abundant number, since it is smaller than the sum of its proper divisors (83097644).

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

81137812 is a wasteful number, since it uses less digits than its factorization.

81137812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35007 (or 35005 counting only the distinct ones).

The product of its digits is 2688, while the sum is 31.

The square root of 81137812 is about 9007.6529684486. The cubic root of 81137812 is about 432.9201139099.

The spelling of 81137812 in words is "eighty-one million, one hundred thirty-seven thousand, eight hundred twelve".