28320581 has 4 divisors (see below), whose sum is σ = 28433664. Its totient is φ = 28207500.

The previous prime is 28320563. The next prime is 28320587. The reversal of 28320581 is 18502382.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28320581 - 2⁶ = 28320517 is a prime.

It is a super-2 number, since 2×28320581² = 1604110616355122, 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 (28320587) 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, 56165 + ... + 56666.

It is an arithmetic number, because the mean of its divisors is an integer number (7108416).

Almost surely, 2^28320581 is an apocalyptic number.

It is an amenable number.

28320581 is a deficient number, since it is larger than the sum of its proper divisors (113083).

28320581 is a wasteful number, since it uses less digits than its factorization.

28320581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113082.

The product of its (nonzero) digits is 3840, while the sum is 29.

The square root of 28320581 is about 5321.7084662728. The cubic root of 28320581 is about 304.8133983554.

The spelling of 28320581 in words is "twenty-eight million, three hundred twenty thousand, five hundred eighty-one".