81521532 has 24 divisors (see below), whose sum is σ = 211352400. Its totient is φ = 27173808.

The previous prime is 81521527. The next prime is 81521543. The reversal of 81521532 is 23512518.

It is a happy number.

81521532 is a `hidden beast` number, since 81 + 52 + 1 + 532 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 81521496 and 81521505.

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, 377307 + ... + 377522.

It is an arithmetic number, because the mean of its divisors is an integer number (8806350).

Almost surely, 2^81521532 is an apocalyptic number.

It is an amenable number.

81521532 is an abundant number, since it is smaller than the sum of its proper divisors (129830868).

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

81521532 is a wasteful number, since it uses less digits than its factorization.

81521532 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 754842 (or 754834 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 81521532 is about 9028.9275110613. The cubic root of 81521532 is about 433.6015015970.

The spelling of 81521532 in words is "eighty-one million, five hundred twenty-one thousand, five hundred thirty-two".