21122208 has 120 divisors (see below), whose sum is σ = 64490580. Its totient is φ = 6773760.

The previous prime is 21122203. The next prime is 21122221. The reversal of 21122208 is 80222112.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20903184 + 219024 = 4572^2 + 468^2 .

It is a super-2 number, since 2×21122208² = 892295341590528, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21122201) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 75028 + ... + 75308.

Almost surely, 2^21122208 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21122208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32245290).

21122208 is an abundant number, since it is smaller than the sum of its proper divisors (43368372).

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

21122208 is a wasteful number, since it uses less digits than its factorization.

21122208 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332 (or 315 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 21122208 is about 4595.8903381173. The cubic root of 21122208 is about 276.4265615760.

The spelling of 21122208 in words is "twenty-one million, one hundred twenty-two thousand, two hundred eight".