21724299 has 12 divisors (see below), whose sum is σ = 31427136. Its totient is φ = 14460912.

The previous prime is 21724271. The next prime is 21724303. The reversal of 21724299 is 99242712.

It is not a de Polignac number, because 21724299 - 2¹⁵ = 21691531 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21724229) 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, 6369 + ... + 9165.

It is an arithmetic number, because the mean of its divisors is an integer number (2618928).

Almost surely, 2^21724299 is an apocalyptic number.

21724299 is a deficient number, since it is larger than the sum of its proper divisors (9702837).

21724299 is a wasteful number, since it uses less digits than its factorization.

21724299 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3666 (or 3663 counting only the distinct ones).

The product of its digits is 18144, while the sum is 36.

The square root of 21724299 is about 4660.9332756434. The cubic root of 21724299 is about 279.0285167599.

The spelling of 21724299 in words is "twenty-one million, seven hundred twenty-four thousand, two hundred ninety-nine".