21122370 has 80 divisors (see below), whose sum is σ = 57629880. Its totient is φ = 5550336.

The previous prime is 21122363. The next prime is 21122383. The reversal of 21122370 is 7322112.

It can be written as a sum of positive squares in 4 ways, for example, as 18584721 + 2537649 = 4311^2 + 1593^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 71944 + ... + 72236.

Almost surely, 2^21122370 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21122370, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28814940).

21122370 is an abundant number, since it is smaller than the sum of its proper divisors (36507510).

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

21122370 is a wasteful number, since it uses less digits than its factorization.

21122370 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 401 (or 392 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 21122370 is about 4595.9079625249. The cubic root of 21122370 is about 276.4272682727.

Adding to 21122370 its reverse (7322112), we get a palindrome (28444482).

The spelling of 21122370 in words is "twenty-one million, one hundred twenty-two thousand, three hundred seventy".