21788816 has 20 divisors (see below), whose sum is σ = 48246912. Its totient is φ = 9338016.

The previous prime is 21788813. The next prime is 21788827. The reversal of 21788816 is 61888712.

It is a Smith number, since the sum of its digits (41) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21788813) 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, 97160 + ... + 97383.

Almost surely, 2^21788816 is an apocalyptic number.

It is an amenable number.

21788816 is an abundant number, since it is smaller than the sum of its proper divisors (26458096).

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

21788816 is a wasteful number, since it uses less digits than its factorization.

21788816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194558 (or 194552 counting only the distinct ones).

The product of its digits is 43008, while the sum is 41.

The square root of 21788816 is about 4667.8491835105. The cubic root of 21788816 is about 279.3044641564.

The spelling of 21788816 in words is "twenty-one million, seven hundred eighty-eight thousand, eight hundred sixteen".