21221200 has 240 divisors, whose sum is σ = 69745536. Its totient is φ = 5990400.

The previous prime is 21221171. The next prime is 21221237. The reversal of 21221200 is 212212.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 400374 + ... + 400426.

Almost surely, 2^21221200 is an apocalyptic number.

21221200 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 21221200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34872768).

21221200 is an abundant number, since it is smaller than the sum of its proper divisors (48524336).

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

21221200 is a wasteful number, since it uses less digits than its factorization.

21221200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102 (or 91 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 21221200 is about 4606.6473709195. The cubic root of 21221200 is about 276.8577251612.

Adding to 21221200 its reverse (212212), we get a palindrome (21433412).

Multiplying 21221200 by its reverse (212212), we get a square (4503393294400 = 2122120²).

21221200 divided by its reverse (212212) gives a square (100 = 10²).

It can be divided in two parts, 212 and 21200, that multiplied together give a square (4494400 = 2120²).

The spelling of 21221200 in words is "twenty-one million, two hundred twenty-one thousand, two hundred".