21604422 has 32 divisors (see below), whose sum is σ = 49900032. Its totient is φ = 6107904.

The previous prime is 21604421. The next prime is 21604439. The reversal of 21604422 is 22440612.

It is a super-3 number, since 3×21604422³ (a number of 23 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent 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 15 ways as a sum of consecutive naturals, for example, 1423 + ... + 6725.

It is an arithmetic number, because the mean of its divisors is an integer number (1559376).

Almost surely, 2^21604422 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21604422, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24950016).

21604422 is an abundant number, since it is smaller than the sum of its proper divisors (28295610).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21604422 is a wasteful number, since it uses less digits than its factorization.

21604422 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5412.

The product of its (nonzero) digits is 768, while the sum is 21.

The square root of 21604422 is about 4648.0557225576. The cubic root of 21604422 is about 278.5143334476.

The spelling of 21604422 in words is "twenty-one million, six hundred four thousand, four hundred twenty-two".