21372180 has 48 divisors (see below), whose sum is σ = 60419520. Its totient is φ = 5644288.

The previous prime is 21372167. The next prime is 21372181. The reversal of 21372180 is 8127312.

It is a self number, because there is not a number n which added to its sum of digits gives 21372180.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21372181) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4756 + ... + 8084.

It is an arithmetic number, because the mean of its divisors is an integer number (1258740).

Almost surely, 2^21372180 is an apocalyptic number.

21372180 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 21372180, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30209760).

21372180 is an abundant number, since it is smaller than the sum of its proper divisors (39047340).

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

21372180 is a wasteful number, since it uses less digits than its factorization.

21372180 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3448 (or 3446 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 21372180 is about 4623.0055158955. The cubic root of 21372180 is about 277.5127500026.

Adding to 21372180 its reverse (8127312), we get a palindrome (29499492).

The spelling of 21372180 in words is "twenty-one million, three hundred seventy-two thousand, one hundred eighty".