21604425 has 24 divisors (see below), whose sum is σ = 37601760. Its totient is φ = 10915200.

The previous prime is 21604421. The next prime is 21604439. The reversal of 21604425 is 52440612.

It is not a de Polignac number, because 21604425 - 2² = 21604421 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21604395 and 21604404.

It is not an unprimeable number, because it can be changed into a prime (21604421) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6156 + ... + 9005.

It is an arithmetic number, because the mean of its divisors is an integer number (1566740).

Almost surely, 2^21604425 is an apocalyptic number.

21604425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21604425 is a deficient number, since it is larger than the sum of its proper divisors (15997335).

21604425 is a wasteful number, since it uses less digits than its factorization.

21604425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15193 (or 15188 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 24.

The square root of 21604425 is about 4648.0560452731. The cubic root of 21604425 is about 278.5143463392.

The spelling of 21604425 in words is "twenty-one million, six hundred four thousand, four hundred twenty-five".