21255210 has 48 divisors (see below), whose sum is σ = 57316896. Its totient is φ = 5667408.

The previous prime is 21255209. The next prime is 21255217. The reversal of 21255210 is 1255212.

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 (21255217) 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, 1944 + ... + 6803.

It is an arithmetic number, because the mean of its divisors is an integer number (1194102).

Almost surely, 2^21255210 is an apocalyptic number.

21255210 is an abundant number, since it is smaller than the sum of its proper divisors (36061686).

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

21255210 is an equidigital number, since it uses as much as digits as its factorization.

21255210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8769 (or 8757 counting only the distinct ones).

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

The square root of 21255210 is about 4610.3372978558. The cubic root of 21255210 is about 277.0055475523.

The spelling of 21255210 in words is "twenty-one million, two hundred fifty-five thousand, two hundred ten".