21624425 has 36 divisors (see below), whose sum is σ = 29578836. Its totient is φ = 15667200.

The previous prime is 21624409. The next prime is 21624443. The reversal of 21624425 is 52442612.

It can be written as a sum of positive squares in 18 ways, for example, as 12845056 + 8779369 = 3584^2 + 2963^2 .

It is not a de Polignac number, because 21624425 - 2⁴ = 21624409 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21624394 and 21624403.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 296189 + ... + 296261.

Almost surely, 2^21624425 is an apocalyptic number.

21624425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21624425 is a deficient number, since it is larger than the sum of its proper divisors (7954411).

21624425 is a wasteful number, since it uses less digits than its factorization.

21624425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158 (or 136 counting only the distinct ones).

The product of its digits is 3840, while the sum is 26.

The square root of 21624425 is about 4650.2069846406. The cubic root of 21624425 is about 278.6002634439.

The spelling of 21624425 in words is "twenty-one million, six hundred twenty-four thousand, four hundred twenty-five".