21265724 has 24 divisors (see below), whose sum is σ = 38102400. Its totient is φ = 10382000.

The previous prime is 21265709. The next prime is 21265747. The reversal of 21265724 is 42756212.

It is a happy number.

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, 59057 + ... + 59415.

It is an arithmetic number, because the mean of its divisors is an integer number (1587600).

Almost surely, 2^21265724 is an apocalyptic number.

It is an amenable number.

21265724 is a deficient number, since it is larger than the sum of its proper divisors (16836676).

21265724 is a wasteful number, since it uses less digits than its factorization.

21265724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 673 (or 671 counting only the distinct ones).

The product of its digits is 6720, while the sum is 29.

The square root of 21265724 is about 4611.4774205237. The cubic root of 21265724 is about 277.0512141009.

The spelling of 21265724 in words is "twenty-one million, two hundred sixty-five thousand, seven hundred twenty-four".