21881200 has 60 divisors (see below), whose sum is σ = 57360168. Its totient is φ = 7955200.

The previous prime is 21881191. The next prime is 21881201. The reversal of 21881200 is 218812.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21881201) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1914 + ... + 6886.

Almost surely, 2^21881200 is an apocalyptic number.

21881200 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 21881200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28680084).

21881200 is an abundant number, since it is smaller than the sum of its proper divisors (35478968).

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

21881200 is a wasteful number, since it uses less digits than its factorization.

21881200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5002 (or 4991 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 22.

The square root of 21881200 is about 4677.7344943894. The cubic root of 21881200 is about 279.6986553919.

Multiplying 21881200 by its reverse (218812), we get a square (4787869134400 = 2188120²).

21881200 divided by its reverse (218812) gives a square (100 = 10²).

It can be divided in two parts, 218 and 81200, that added together give a palindrome (81418).

The spelling of 21881200 in words is "twenty-one million, eight hundred eighty-one thousand, two hundred".