21753424 has 40 divisors (see below), whose sum is σ = 52550208. Its totient is φ = 8474880.

The previous prime is 21753419. The next prime is 21753533. The reversal of 21753424 is 42435712.

It is a super-2 number, since 2×21753424² = 946422911447552, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a junction number, because it is equal to n+sod(n) for n = 21753392 and 21753401.

It is a congruent number.

It is an unprimeable number.

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 in 7 ways as a sum of consecutive naturals, for example, 7597 + ... + 10060.

Almost surely, 2^21753424 is an apocalyptic number.

It is an amenable number.

21753424 is an abundant number, since it is smaller than the sum of its proper divisors (30796784).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21753424 is a wasteful number, since it uses less digits than its factorization.

21753424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17683 (or 17677 counting only the distinct ones).

The product of its digits is 6720, while the sum is 28.

The square root of 21753424 is about 4664.0566034301. The cubic root of 21753424 is about 279.1531556343.

The spelling of 21753424 in words is "twenty-one million, seven hundred fifty-three thousand, four hundred twenty-four".