21735424 has 24 divisors (see below), whose sum is σ = 43464330. Its totient is φ = 10866688.

The previous prime is 21735421. The next prime is 21735431. The reversal of 21735424 is 42453712.

It can be written as a sum of positive squares in only one way, i.e., 11289600 + 10445824 = 3360^2 + 3232^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21735392 and 21735401.

It is not an unprimeable number, because it can be changed into a prime (21735421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3259 + ... + 7354.

Almost surely, 2^21735424 is an apocalyptic number.

It is an amenable number.

21735424 is a deficient number, since it is larger than the sum of its proper divisors (21728906).

21735424 is an equidigital number, since it uses as much as digits as its factorization.

21735424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10635 (or 10615 counting only the distinct ones).

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

The square root of 21735424 is about 4662.1265534089. The cubic root of 21735424 is about 279.0761387417.

The spelling of 21735424 in words is "twenty-one million, seven hundred thirty-five thousand, four hundred twenty-four".