21788916 has 24 divisors (see below), whose sum is σ = 51367680. Its totient is φ = 7187712.

The previous prime is 21788909. The next prime is 21788927. The reversal of 21788916 is 61988712.

It is a super-3 number, since 3×21788916³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8196 + ... + 10523.

It is an arithmetic number, because the mean of its divisors is an integer number (2140320).

Almost surely, 2^21788916 is an apocalyptic number.

It is an amenable number.

21788916 is an abundant number, since it is smaller than the sum of its proper divisors (29578764).

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

21788916 is a wasteful number, since it uses less digits than its factorization.

21788916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18823 (or 18821 counting only the distinct ones).

The product of its digits is 48384, while the sum is 42.

The square root of 21788916 is about 4667.8598950697. The cubic root of 21788916 is about 279.3048914460.

The spelling of 21788916 in words is "twenty-one million, seven hundred eighty-eight thousand, nine hundred sixteen".