21286724 has 12 divisors (see below), whose sum is σ = 37545984. Its totient is φ = 10559304.

The previous prime is 21286717. The next prime is 21286751. The reversal of 21286724 is 42768212.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20444 + ... + 21459.

It is an arithmetic number, because the mean of its divisors is an integer number (3128832).

Almost surely, 2^21286724 is an apocalyptic number.

It is an amenable number.

21286724 is a deficient number, since it is larger than the sum of its proper divisors (16259260).

21286724 is a wasteful number, since it uses less digits than its factorization.

21286724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42034 (or 42032 counting only the distinct ones).

The product of its digits is 10752, while the sum is 32.

The square root of 21286724 is about 4613.7537862352. The cubic root of 21286724 is about 277.1423805467.

The spelling of 21286724 in words is "twenty-one million, two hundred eighty-six thousand, seven hundred twenty-four".