81307536 has 40 divisors (see below), whose sum is σ = 221101920. Its totient is φ = 25675776.

The previous prime is 81307531. The next prime is 81307543. The reversal of 81307536 is 63570318.

It is a happy number.

It is a super-2 number, since 2×81307536² = 13221830820782592, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81307497 and 81307506.

It is not an unprimeable number, because it can be changed into a prime (81307531) 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, 43665 + ... + 45488.

It is an arithmetic number, because the mean of its divisors is an integer number (5527548).

Almost surely, 2^81307536 is an apocalyptic number.

It is an amenable number.

81307536 is an abundant number, since it is smaller than the sum of its proper divisors (139794384).

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

81307536 is a wasteful number, since it uses less digits than its factorization.

81307536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89183 (or 89177 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 33.

The square root of 81307536 is about 9017.0691469013. The cubic root of 81307536 is about 433.2217643080.

The spelling of 81307536 in words is "eighty-one million, three hundred seven thousand, five hundred thirty-six".