81540536 has 32 divisors (see below), whose sum is σ = 190615680. Its totient is φ = 31768800.

The previous prime is 81540523. The next prime is 81540559. The reversal of 81540536 is 63504518.

It is a happy number.

It is a super-2 number, since 2×81540536² = 13297718022334592, which contains 22 as substring.

It is a Smith number, since the sum of its digits (32) coincides with the sum of the digits of its prime factors.

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, 65570 + ... + 66801.

It is an arithmetic number, because the mean of its divisors is an integer number (5956740).

Almost surely, 2^81540536 is an apocalyptic number.

It is an amenable number.

81540536 is an abundant number, since it is smaller than the sum of its proper divisors (109075144).

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

81540536 is a wasteful number, since it uses less digits than its factorization.

81540536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132395 (or 132391 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 32.

The square root of 81540536 is about 9029.9798449387. The cubic root of 81540536 is about 433.6351921755.

The spelling of 81540536 in words is "eighty-one million, five hundred forty thousand, five hundred thirty-six".