21222800 has 60 divisors (see below), whose sum is σ = 54004356. Its totient is φ = 7987200.

The previous prime is 21222787. The next prime is 21222847. The reversal of 21222800 is 822212.

It can be written as a sum of positive squares in 6 ways, for example, as 2835856 + 18386944 = 1684^2 + 4288^2 .

It is a Harshad number since it is a multiple of its sum of digits (17).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5240 + ... + 8360.

Almost surely, 2^21222800 is an apocalyptic number.

21222800 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 21222800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27002178).

21222800 is an abundant number, since it is smaller than the sum of its proper divisors (32781556).

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

21222800 is a wasteful number, since it uses less digits than its factorization.

21222800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3156 (or 3145 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 17.

The square root of 21222800 is about 4606.8210297341. The cubic root of 21222800 is about 276.8646830025.

It can be divided in two parts, 21222 and 800, that added together give a palindrome (22022).

The spelling of 21222800 in words is "twenty-one million, two hundred twenty-two thousand, eight hundred".