21121200 has 90 divisors (see below), whose sum is σ = 73308924. Its totient is φ = 5631360.

The previous prime is 21121187. The next prime is 21121201. The reversal of 21121200 is 212112.

It is a tau number, because it is divible by the number of its divisors (90).

It is a super-2 number, since 2×21121200² = 892210178880000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (21121201) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 667 + ... + 6533.

Almost surely, 2^21121200 is an apocalyptic number.

21121200 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 21121200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36654462).

21121200 is an abundant number, since it is smaller than the sum of its proper divisors (52187724).

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

21121200 is a wasteful number, since it uses less digits than its factorization.

21121200 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5891 (or 5877 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 21121200 is about 4595.7806736179. The cubic root of 21121200 is about 276.4221642704.

Adding to 21121200 its reverse (212112), we get a palindrome (21333312).

It can be divided in two parts, 21121 and 200, that added together give a triangular number (21321 = T₂₀₆).

The spelling of 21121200 in words is "twenty-one million, one hundred twenty-one thousand, two hundred".