21724496 has 10 divisors (see below), whose sum is σ = 42091242. Its totient is φ = 10862240.

The previous prime is 21724457. The next prime is 21724499. The reversal of 21724496 is 69442712.

It can be written as a sum of positive squares in only one way, i.e., 13104400 + 8620096 = 3620^2 + 2936^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21724499) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 678875 + ... + 678906.

Almost surely, 2^21724496 is an apocalyptic number.

It is an amenable number.

21724496 is a deficient number, since it is larger than the sum of its proper divisors (20366746).

21724496 is a wasteful number, since it uses less digits than its factorization.

21724496 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1357789 (or 1357783 counting only the distinct ones).

The product of its digits is 24192, while the sum is 35.

The square root of 21724496 is about 4660.9544087021. The cubic root of 21724496 is about 279.0293601849.

The spelling of 21724496 in words is "twenty-one million, seven hundred twenty-four thousand, four hundred ninety-six".