21921424 has 30 divisors (see below), whose sum is σ = 49408854. Its totient is φ = 9394560.

The previous prime is 21921413. The next prime is 21921437. The reversal of 21921424 is 42412912.

It can be written as a sum of positive squares in only one way, i.e., 16257024 + 5664400 = 4032^2 + 2380^2 .

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 5 ways as a sum of consecutive naturals, for example, 13197 + ... + 14764.

Almost surely, 2^21921424 is an apocalyptic number.

It is an amenable number.

21921424 is an abundant number, since it is smaller than the sum of its proper divisors (27487430).

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

21921424 is a wasteful number, since it uses less digits than its factorization.

21921424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27983 (or 27970 counting only the distinct ones).

The product of its digits is 1152, while the sum is 25.

The square root of 21921424 is about 4682.0320374812. The cubic root of 21921424 is about 279.8699395961.

The spelling of 21921424 in words is "twenty-one million, nine hundred twenty-one thousand, four hundred twenty-four".