21744724 has 12 divisors (see below), whose sum is σ = 38086048. Its totient is φ = 10863000.

The previous prime is 21744631. The next prime is 21744727. The reversal of 21744724 is 42744712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21744727) 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, 7249 + ... + 9799.

Almost surely, 2^21744724 is an apocalyptic number.

It is an amenable number.

21744724 is a deficient number, since it is larger than the sum of its proper divisors (16341324).

21744724 is a wasteful number, since it uses less digits than its factorization.

21744724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4686 (or 4684 counting only the distinct ones).

The product of its digits is 12544, while the sum is 31.

The square root of 21744724 is about 4663.1238456640. The cubic root of 21744724 is about 279.1159361098.

The spelling of 21744724 in words is "twenty-one million, seven hundred forty-four thousand, seven hundred twenty-four".