20989788 has 12 divisors (see below), whose sum is σ = 48976200. Its totient is φ = 6996592.

The previous prime is 20989769. The next prime is 20989789. The reversal of 20989788 is 88798902.

It is a tau number, because it is divible by the number of its divisors (12).

It is a self number, because there is not a number n which added to its sum of digits gives 20989788.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20989789) 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, 874563 + ... + 874586.

It is an arithmetic number, because the mean of its divisors is an integer number (4081350).

Almost surely, 2^20989788 is an apocalyptic number.

It is an amenable number.

20989788 is an abundant number, since it is smaller than the sum of its proper divisors (27986412).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20989788 is a wasteful number, since it uses less digits than its factorization.

20989788 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1749156 (or 1749154 counting only the distinct ones).

The product of its (nonzero) digits is 580608, while the sum is 51.

The square root of 20989788 is about 4581.4613389180. The cubic root of 20989788 is about 275.8476895400.

The spelling of 20989788 in words is "twenty million, nine hundred eighty-nine thousand, seven hundred eighty-eight".