20807491 has 4 divisors (see below), whose sum is σ = 20888712. Its totient is φ = 20726272.

The previous prime is 20807483. The next prime is 20807503. The reversal of 20807491 is 19470802.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20807491 - 2³ = 20807483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20807191) 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, 40225 + ... + 40738.

It is an arithmetic number, because the mean of its divisors is an integer number (5222178).

Almost surely, 2^20807491 is an apocalyptic number.

20807491 is a deficient number, since it is larger than the sum of its proper divisors (81221).

20807491 is an equidigital number, since it uses as much as digits as its factorization.

20807491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81220.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 20807491 is about 4561.5228816701. The cubic root of 20807491 is about 275.0467843269.

The spelling of 20807491 in words is "twenty million, eight hundred seven thousand, four hundred ninety-one".