20638711 has 4 divisors (see below), whose sum is σ = 21196552. Its totient is φ = 20080872.

The previous prime is 20638699. The next prime is 20638729. The reversal of 20638711 is 11783602.

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 20638711 - 2²¹ = 18541559 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20638711.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20638741) 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, 278865 + ... + 278938.

It is an arithmetic number, because the mean of its divisors is an integer number (5299138).

Almost surely, 2^20638711 is an apocalyptic number.

20638711 is a deficient number, since it is larger than the sum of its proper divisors (557841).

20638711 is an equidigital number, since it uses as much as digits as its factorization.

20638711 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 557840.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 20638711 is about 4542.9848117730. The cubic root of 20638711 is about 274.3010836011.

The spelling of 20638711 in words is "twenty million, six hundred thirty-eight thousand, seven hundred eleven".