21164580 has 72 divisors (see below), whose sum is σ = 64576512. Its totient is φ = 5610816.

The previous prime is 21164579. The next prime is 21164581. The reversal of 21164580 is 8546112.

21164580 is a `hidden beast` number, since 2 + 11 + 645 + 8 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (21164579) and next prime (21164581).

It is not an unprimeable number, because it can be changed into a prime (21164581) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 55069 + ... + 55451.

It is an arithmetic number, because the mean of its divisors is an integer number (896896).

Almost surely, 2^21164580 is an apocalyptic number.

21164580 is a gapful number since it is divisible by the number (20) 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 21164580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32288256).

21164580 is an abundant number, since it is smaller than the sum of its proper divisors (43411932).

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

21164580 is a wasteful number, since it uses less digits than its factorization.

21164580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 705 (or 700 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21164580 is about 4600.4977991517. The cubic root of 21164580 is about 276.6112790528.

The spelling of 21164580 in words is "twenty-one million, one hundred sixty-four thousand, five hundred eighty".