72320581 has 4 divisors (see below), whose sum is σ = 73066252. Its totient is φ = 71574912.

The previous prime is 72320561. The next prime is 72320587. The reversal of 72320581 is 18502327.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18502327 = 23 ⋅804449.

It can be written as a sum of positive squares in 2 ways, for example, as 53787556 + 18533025 = 7334^2 + 4305^2 .

It is a cyclic number.

It is not a de Polignac number, because 72320581 - 2²⁵ = 38766149 is a prime.

It is a super-2 number, since 2×72320581² = 10460532872355122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (72320587) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 372690 + ... + 372883.

It is an arithmetic number, because the mean of its divisors is an integer number (18266563).

Almost surely, 2^72320581 is an apocalyptic number.

It is an amenable number.

72320581 is a deficient number, since it is larger than the sum of its proper divisors (745671).

72320581 is an equidigital number, since it uses as much as digits as its factorization.

72320581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 745670.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 72320581 is about 8504.1508100456. The cubic root of 72320581 is about 416.6332906243.

The spelling of 72320581 in words is "seventy-two million, three hundred twenty thousand, five hundred eighty-one".