21604407 has 8 divisors (see below), whose sum is σ = 31424640. Its totient is φ = 13093560.

The previous prime is 21604397. The next prime is 21604421. The reversal of 21604407 is 70440612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21604407 - 2⁸ = 21604151 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21604487) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 327307 + ... + 327372.

It is an arithmetic number, because the mean of its divisors is an integer number (3928080).

Almost surely, 2^21604407 is an apocalyptic number.

21604407 is a deficient number, since it is larger than the sum of its proper divisors (9820233).

21604407 is a wasteful number, since it uses less digits than its factorization.

21604407 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 654693.

The product of its (nonzero) digits is 1344, while the sum is 24.

The square root of 21604407 is about 4648.0541089794. The cubic root of 21604407 is about 278.5142689899.

The spelling of 21604407 in words is "twenty-one million, six hundred four thousand, four hundred seven".