21604411 has 4 divisors (see below), whose sum is σ = 22188352. Its totient is φ = 21020472.

The previous prime is 21604397. The next prime is 21604421. The reversal of 21604411 is 11440612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21604411 - 2⁵ = 21604379 is a prime.

It is a Duffinian number.

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 3 ways as a sum of consecutive naturals, for example, 291915 + ... + 291988.

It is an arithmetic number, because the mean of its divisors is an integer number (5547088).

Almost surely, 2^21604411 is an apocalyptic number.

21604411 is a deficient number, since it is larger than the sum of its proper divisors (583941).

21604411 is an equidigital number, since it uses as much as digits as its factorization.

21604411 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 583940.

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 21604411 is about 4648.0545392669. The cubic root of 21604411 is about 278.5142861786.

The spelling of 21604411 in words is "twenty-one million, six hundred four thousand, four hundred eleven".