81490724 has 72 divisors (see below), whose sum is σ = 180670392. Its totient is φ = 31933440.

The previous prime is 81490697. The next prime is 81490729. The reversal of 81490724 is 42709418.

It can be written as a sum of positive squares in 4 ways, for example, as 51984100 + 29506624 = 7210^2 + 5432^2 .

It is not an unprimeable number, because it can be changed into a prime (81490729) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 122954 + ... + 123614.

It is an arithmetic number, because the mean of its divisors is an integer number (2509311).

Almost surely, 2^81490724 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81490724, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (90335196).

81490724 is an abundant number, since it is smaller than the sum of its proper divisors (99179668).

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

81490724 is a wasteful number, since it uses less digits than its factorization.

81490724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 733 (or 724 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 35.

The square root of 81490724 is about 9027.2212778906. The cubic root of 81490724 is about 433.5468735830.

The spelling of 81490724 in words is "eighty-one million, four hundred ninety thousand, seven hundred twenty-four".