21115164 has 48 divisors (see below), whose sum is σ = 57689856. Its totient is φ = 5884800.

The previous prime is 21115141. The next prime is 21115189. The reversal of 21115164 is 46151112.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21115164.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 379 + ... + 6509.

It is an arithmetic number, because the mean of its divisors is an integer number (1201872).

Almost surely, 2^21115164 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 21115164, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28844928).

21115164 is an abundant number, since it is smaller than the sum of its proper divisors (36574692).

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

21115164 is a wasteful number, since it uses less digits than its factorization.

21115164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6186 (or 6184 counting only the distinct ones).

The product of its digits is 240, while the sum is 21.

The square root of 21115164 is about 4595.1239373928. The cubic root of 21115164 is about 276.3958298584.

Adding to 21115164 its reverse (46151112), we get a palindrome (67266276).

The spelling of 21115164 in words is "twenty-one million, one hundred fifteen thousand, one hundred sixty-four".