21208122 has 32 divisors (see below), whose sum is σ = 50756160. Its totient is φ = 6525360.

The previous prime is 21208097. The next prime is 21208127. The reversal of 21208122 is 22180212.

It is a happy number.

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 = 21208095 and 21208104.

It is not an unprimeable number, because it can be changed into a prime (21208127) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14404 + ... + 15807.

It is an arithmetic number, because the mean of its divisors is an integer number (1586130).

Almost surely, 2^21208122 is an apocalyptic number.

21208122 is an abundant number, since it is smaller than the sum of its proper divisors (29548038).

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

21208122 is a wasteful number, since it uses less digits than its factorization.

21208122 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30235 (or 30229 counting only the distinct ones).

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

The square root of 21208122 is about 4605.2276816679. The cubic root of 21208122 is about 276.8008403892.

Adding to 21208122 its reverse (22180212), we get a palindrome (43388334).

The spelling of 21208122 in words is "twenty-one million, two hundred eight thousand, one hundred twenty-two".