21738824 has 16 divisors (see below), whose sum is σ = 40988220. Its totient is φ = 10808640.

The previous prime is 21738823. The next prime is 21738833. The reversal of 21738824 is 42883712.

It can be written as a sum of positive squares in 2 ways, for example, as 20702500 + 1036324 = 4550^2 + 1018^2 .

It is not an unprimeable number, because it can be changed into a prime (21738823) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6059 + ... + 8954.

Almost surely, 2^21738824 is an apocalyptic number.

It is an amenable number.

21738824 is a deficient number, since it is larger than the sum of its proper divisors (19249396).

21738824 is a wasteful number, since it uses less digits than its factorization.

21738824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15200 (or 15196 counting only the distinct ones).

The product of its digits is 21504, while the sum is 35.

The square root of 21738824 is about 4662.4911796163. The cubic root of 21738824 is about 279.0906896334.

The spelling of 21738824 in words is "twenty-one million, seven hundred thirty-eight thousand, eight hundred twenty-four".