21573724 has 24 divisors (see below), whose sum is σ = 39559968. Its totient is φ = 10274880.

The previous prime is 21573719. The next prime is 21573751. The reversal of 21573724 is 42737512.

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38454 + ... + 39010.

It is an arithmetic number, because the mean of its divisors is an integer number (1648332).

Almost surely, 2^21573724 is an apocalyptic number.

It is an amenable number.

21573724 is a deficient number, since it is larger than the sum of its proper divisors (17986244).

21573724 is a wasteful number, since it uses less digits than its factorization.

21573724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1005 (or 1003 counting only the distinct ones).

The product of its digits is 11760, while the sum is 31.

The square root of 21573724 is about 4644.7523077124. The cubic root of 21573724 is about 278.3823560569.

The spelling of 21573724 in words is "twenty-one million, five hundred seventy-three thousand, seven hundred twenty-four".