21055122 has 48 divisors (see below), whose sum is σ = 50944608. Its totient is φ = 6229440.

The previous prime is 21055087. The next prime is 21055123. The reversal of 21055122 is 22155012.

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

It is a junction number, because it is equal to n+sod(n) for n = 21055095 and 21055104.

It is not an unprimeable number, because it can be changed into a prime (21055123) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7278 + ... + 9750.

It is an arithmetic number, because the mean of its divisors is an integer number (1061346).

Almost surely, 2^21055122 is an apocalyptic number.

21055122 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21055122, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25472304).

21055122 is an abundant number, since it is smaller than the sum of its proper divisors (29889486).

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

21055122 is a wasteful number, since it uses less digits than its factorization.

21055122 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2535 (or 2532 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 21055122 is about 4588.5860567282. The cubic root of 21055122 is about 276.1335994661.

It can be divided in two parts, 2105 and 5122, that added together give a palindrome (7227).

The spelling of 21055122 in words is "twenty-one million, fifty-five thousand, one hundred twenty-two".