20718641 has 4 divisors (see below), whose sum is σ = 21002532. Its totient is φ = 20434752.

The previous prime is 20718637. The next prime is 20718661. The reversal of 20718641 is 14681702.

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

It can be written as a sum of positive squares in 2 ways, for example, as 4080400 + 16638241 = 2020^2 + 4079^2 .

It is a cyclic number.

It is not a de Polignac number, because 20718641 - 2² = 20718637 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20718661) 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, 141836 + ... + 141981.

It is an arithmetic number, because the mean of its divisors is an integer number (5250633).

Almost surely, 2^20718641 is an apocalyptic number.

It is an amenable number.

20718641 is a deficient number, since it is larger than the sum of its proper divisors (283891).

20718641 is an equidigital number, since it uses as much as digits as its factorization.

20718641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 283890.

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 20718641 is about 4551.7733906687. The cubic root of 20718641 is about 274.6547336368.

The spelling of 20718641 in words is "twenty million, seven hundred eighteen thousand, six hundred forty-one".