21724113 has 16 divisors (see below), whose sum is σ = 31176576. Its totient is φ = 13405440.

The previous prime is 21724111. The next prime is 21724133. The reversal of 21724113 is 31142712.

It is not a de Polignac number, because 21724113 - 2¹ = 21724111 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21724113.

It is not an unprimeable number, because it can be changed into a prime (21724111) 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, 381 + ... + 6602.

It is an arithmetic number, because the mean of its divisors is an integer number (1948536).

Almost surely, 2^21724113 is an apocalyptic number.

It is an amenable number.

21724113 is a deficient number, since it is larger than the sum of its proper divisors (9452463).

21724113 is a wasteful number, since it uses less digits than its factorization.

21724113 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7064.

The product of its digits is 336, while the sum is 21.

The square root of 21724113 is about 4660.9133225152. The cubic root of 21724113 is about 279.0277204250.

Adding to 21724113 its reverse (31142712), we get a palindrome (52866825).

The spelling of 21724113 in words is "twenty-one million, seven hundred twenty-four thousand, one hundred thirteen".