21255212 has 24 divisors (see below), whose sum is σ = 41889792. Its totient is φ = 9349200.

The previous prime is 21255209. The next prime is 21255217.

It is a happy number.

21255212 is nontrivially palindromic in base 10.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 6428 + ... + 9155.

It is an arithmetic number, because the mean of its divisors is an integer number (1745408).

Almost surely, 2^21255212 is an apocalyptic number.

21255212 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21255212 is a deficient number, since it is larger than the sum of its proper divisors (20634580).

21255212 is a wasteful number, since it uses less digits than its factorization.

21255212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15629 (or 15627 counting only the distinct ones).

The product of its digits is 400, while the sum is 20.

The square root of 21255212 is about 4610.3375147596. The cubic root of 21255212 is about 277.0055562406.

It can be divided in two parts, 2125 and 5212, that added together give a palindrome (7337).

The spelling of 21255212 in words is "twenty-one million, two hundred fifty-five thousand, two hundred twelve".