21250724 has 12 divisors (see below), whose sum is σ = 40569648. Its totient is φ = 9659400.

The previous prime is 21250709. The next prime is 21250771. The reversal of 21250724 is 42705212.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21250724.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 241442 + ... + 241529.

It is an arithmetic number, because the mean of its divisors is an integer number (3380804).

Almost surely, 2^21250724 is an apocalyptic number.

It is an amenable number.

21250724 is a deficient number, since it is larger than the sum of its proper divisors (19318924).

21250724 is a wasteful number, since it uses less digits than its factorization.

21250724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 482986 (or 482984 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 23.

The square root of 21250724 is about 4609.8507568033. The cubic root of 21250724 is about 276.9860584589.

Adding to 21250724 its reverse (42705212), we get a palindrome (63955936).

The spelling of 21250724 in words is "twenty-one million, two hundred fifty thousand, seven hundred twenty-four".