21055164 has 48 divisors (see below), whose sum is σ = 53343360. Its totient is φ = 6425280.

The previous prime is 21055147. The next prime is 21055207. The reversal of 21055164 is 46155012.

It is a congruent number.

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 15 ways as a sum of consecutive naturals, for example, 21199 + ... + 22169.

It is an arithmetic number, because the mean of its divisors is an integer number (1111320).

Almost surely, 2^21055164 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21055164, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26671680).

21055164 is an abundant number, since it is smaller than the sum of its proper divisors (32288196).

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

21055164 is a wasteful number, since it uses less digits than its factorization.

21055164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1130 (or 1128 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 21055164 is about 4588.5906332991. The cubic root of 21055164 is about 276.1337830731.

The spelling of 21055164 in words is "twenty-one million, fifty-five thousand, one hundred sixty-four".