21164416 has 128 divisors (see below), whose sum is σ = 54835200. Its totient is φ = 7907328.

The previous prime is 21164401. The next prime is 21164431. The reversal of 21164416 is 61446112.

It is an interprime number because it is at equal distance from previous prime (21164401) and next prime (21164431).

It is a tau number, because it is divible by the number of its divisors (128).

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, 267865 + ... + 267943.

It is an arithmetic number, because the mean of its divisors is an integer number (428400).

Almost surely, 2^21164416 is an apocalyptic number.

21164416 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21164416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27417600).

21164416 is an abundant number, since it is smaller than the sum of its proper divisors (33670784).

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

21164416 is a wasteful number, since it uses less digits than its factorization.

21164416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136 (or 124 counting only the distinct ones).

The product of its digits is 1152, while the sum is 25.

The square root of 21164416 is about 4600.4799749591. The cubic root of 21164416 is about 276.6105645829.

The spelling of 21164416 in words is "twenty-one million, one hundred sixty-four thousand, four hundred sixteen".