81509832 has 48 divisors (see below), whose sum is σ = 233744940. Its totient is φ = 25571328.

The previous prime is 81509809. The next prime is 81509833. The reversal of 81509832 is 23890518.

It can be written as a sum of positive squares in 2 ways, for example, as 80892036 + 617796 = 8994^2 + 786^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (81509833) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 32073 + ... + 34520.

Almost surely, 2^81509832 is an apocalyptic number.

It is an amenable number.

81509832 is an abundant number, since it is smaller than the sum of its proper divisors (152235108).

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

81509832 is a wasteful number, since it uses less digits than its factorization.

81509832 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66622 (or 66615 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 81509832 is about 9028.2795703279. The cubic root of 81509832 is about 433.5807570560.

The spelling of 81509832 in words is "eighty-one million, five hundred nine thousand, eight hundred thirty-two".