20328581 has 32 divisors (see below), whose sum is σ = 26342400. Its totient is φ = 15579648.

The previous prime is 20328569. The next prime is 20328589. The reversal of 20328581 is 18582302.

It is not a de Polignac number, because 20328581 - 2²² = 16134277 is a prime.

It is a super-2 number, since 2×20328581² = 826502410947122, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20328589) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 209525 + ... + 209621.

It is an arithmetic number, because the mean of its divisors is an integer number (823200).

Almost surely, 2^20328581 is an apocalyptic number.

It is an amenable number.

20328581 is a deficient number, since it is larger than the sum of its proper divisors (6013819).

20328581 is an equidigital number, since it uses as much as digits as its factorization.

20328581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 178 (or 164 counting only the distinct ones).

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

The square root of 20328581 is about 4508.7227681462. The cubic root of 20328581 is about 272.9202045990.

The spelling of 20328581 in words is "twenty million, three hundred twenty-eight thousand, five hundred eighty-one".