21604770 has 96 divisors (see below), whose sum is σ = 62112960. Its totient is φ = 5166720.

The previous prime is 21604747. The next prime is 21604783. The reversal of 21604770 is 7740612.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 137532 + ... + 137688.

It is an arithmetic number, because the mean of its divisors is an integer number (647010).

Almost surely, 2^21604770 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21604770, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31056480).

21604770 is an abundant number, since it is smaller than the sum of its proper divisors (40508190).

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

21604770 is a wasteful number, since it uses less digits than its factorization.

21604770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320 (or 317 counting only the distinct ones).

The product of its (nonzero) digits is 2352, while the sum is 27.

The square root of 21604770 is about 4648.0931574141. The cubic root of 21604770 is about 278.5158288586.

The spelling of 21604770 in words is "twenty-one million, six hundred four thousand, seven hundred seventy".