21724833 has 16 divisors (see below), whose sum is σ = 31322816. Its totient is φ = 13314240.

The previous prime is 21724819. The next prime is 21724841. The reversal of 21724833 is 33842712.

It is not a de Polignac number, because 21724833 - 2⁹ = 21724321 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21724833.

It is not an unprimeable number, because it can be changed into a prime (21724133) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9798 + ... + 11808.

It is an arithmetic number, because the mean of its divisors is an integer number (1957676).

Almost surely, 2^21724833 is an apocalyptic number.

It is an amenable number.

21724833 is a deficient number, since it is larger than the sum of its proper divisors (9597983).

21724833 is a wasteful number, since it uses less digits than its factorization.

21724833 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2304.

The product of its digits is 8064, while the sum is 30.

The square root of 21724833 is about 4660.9905599561. The cubic root of 21724833 is about 279.0308029865.

The spelling of 21724833 in words is "twenty-one million, seven hundred twenty-four thousand, eight hundred thirty-three".