21724574 has 4 divisors (see below), whose sum is σ = 32586864. Its totient is φ = 10862286.

The previous prime is 21724553. The next prime is 21724607. The reversal of 21724574 is 47542712.

It is a semiprime because it is the product of two primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21724574.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5431142 + ... + 5431145.

It is an arithmetic number, because the mean of its divisors is an integer number (8146716).

Almost surely, 2^21724574 is an apocalyptic number.

21724574 is a deficient number, since it is larger than the sum of its proper divisors (10862290).

21724574 is a wasteful number, since it uses less digits than its factorization.

21724574 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10862289.

The product of its digits is 15680, while the sum is 32.

The square root of 21724574 is about 4660.9627760796. The cubic root of 21724574 is about 279.0296941284.

The spelling of 21724574 in words is "twenty-one million, seven hundred twenty-four thousand, five hundred seventy-four".