21222000 has 200 divisors, whose sum is σ = 77240592. Its totient is φ = 5616000.

The previous prime is 21221953. The next prime is 21222013. The reversal of 21222000 is 22212.

It is a tau number, because it is divible by the number of its divisors (200).

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

It is a congruent number.

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 39 ways as a sum of consecutive naturals, for example, 161935 + ... + 162065.

Almost surely, 2^21222000 is an apocalyptic number.

21222000 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 21222000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38620296).

21222000 is an abundant number, since it is smaller than the sum of its proper divisors (56018592).

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

21222000 is a wasteful number, since it uses less digits than its factorization.

21222000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 166 (or 141 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

The square root of 21222000 is about 4606.7342011451. The cubic root of 21222000 is about 276.8612041255.

Adding to 21222000 its reverse (22212), we get a palindrome (21244212).

The spelling of 21222000 in words is "twenty-one million, two hundred twenty-two thousand".