21938784 has 48 divisors (see below), whose sum is σ = 65818368. Its totient is φ = 6268032.

The previous prime is 21938779. The next prime is 21938831. The reversal of 21938784 is 48783912.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15652 + ... + 16995.

It is an arithmetic number, because the mean of its divisors is an integer number (1371216).

Almost surely, 2^21938784 is an apocalyptic number.

21938784 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21938784 is an abundant number, since it is smaller than the sum of its proper divisors (43879584).

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

21938784 is a wasteful number, since it uses less digits than its factorization.

21938784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32667 (or 32659 counting only the distinct ones).

The product of its digits is 96768, while the sum is 42.

The square root of 21938784 is about 4683.8855664928. The cubic root of 21938784 is about 279.9437982437.

It can be divided in two parts, 21938 and 784, that added together give a palindrome (22722).

The spelling of 21938784 in words is "twenty-one million, nine hundred thirty-eight thousand, seven hundred eighty-four".