21404572 has 24 divisors (see below), whose sum is σ = 43685600. Its totient is φ = 9172800.

The previous prime is 21404569. The next prime is 21404597. The reversal of 21404572 is 27540412.

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, 6429 + ... + 9172.

Almost surely, 2^21404572 is an apocalyptic number.

It is an amenable number.

21404572 is an abundant number, since it is smaller than the sum of its proper divisors (22281028).

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

21404572 is a wasteful number, since it uses less digits than its factorization.

21404572 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15626 (or 15610 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 25.

The square root of 21404572 is about 4626.5075380896. The cubic root of 21404572 is about 277.6528800756.

Adding to 21404572 its reverse (27540412), we get a palindrome (48944984).

The spelling of 21404572 in words is "twenty-one million, four hundred four thousand, five hundred seventy-two".