21930784 has 12 divisors (see below), whose sum is σ = 43176294. Its totient is φ = 10965376.

The previous prime is 21930743. The next prime is 21930791. The reversal of 21930784 is 48703912.

It can be written as a sum of positive squares in only one way, i.e., 19891600 + 2039184 = 4460^2 + 1428^2 .

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342637 + ... + 342700.

Almost surely, 2^21930784 is an apocalyptic number.

It is an amenable number.

21930784 is a deficient number, since it is larger than the sum of its proper divisors (21245510).

21930784 is an equidigital number, since it uses as much as digits as its factorization.

21930784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 685347 (or 685339 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 21930784 is about 4683.0314967978. The cubic root of 21930784 is about 279.9097668428.

The spelling of 21930784 in words is "twenty-one million, nine hundred thirty thousand, seven hundred eighty-four".