21724612 has 36 divisors (see below), whose sum is σ = 47058816. Its totient is φ = 8592480.

The previous prime is 21724609. The next prime is 21724613. The reversal of 21724612 is 21642712.

It is not an unprimeable number, because it can be changed into a prime (21724613) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2437 + ... + 7027.

Almost surely, 2^21724612 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21724612, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23529408).

21724612 is an abundant number, since it is smaller than the sum of its proper divisors (25334204).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21724612 is a wasteful number, since it uses less digits than its factorization.

21724612 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4628 (or 4613 counting only the distinct ones).

The product of its digits is 1344, while the sum is 25.

The square root of 21724612 is about 4660.9668524889. The cubic root of 21724612 is about 279.0298568186.

The spelling of 21724612 in words is "twenty-one million, seven hundred twenty-four thousand, six hundred twelve".