21222100 has 36 divisors (see below), whose sum is σ = 48059424. Its totient is φ = 8118880.

The previous prime is 21222043. The next prime is 21222143. The reversal of 21222100 is 122212.

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 11 ways as a sum of consecutive naturals, for example, 2314 + ... + 6913.

It is an arithmetic number, because the mean of its divisors is an integer number (1334984).

Almost surely, 2^21222100 is an apocalyptic number.

21222100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21222100 is an abundant number, since it is smaller than the sum of its proper divisors (26837324).

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

21222100 is a wasteful number, since it uses less digits than its factorization.

21222100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9264 (or 9257 counting only the distinct ones).

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

The square root of 21222100 is about 4606.7450548082. The cubic root of 21222100 is about 276.8616389899.

Adding to 21222100 its reverse (122212), we get a palindrome (21344312).

The spelling of 21222100 in words is "twenty-one million, two hundred twenty-two thousand, one hundred".