31221228 has 18 divisors (see below), whose sum is σ = 72894724. Its totient is φ = 10400624.

The previous prime is 31221227. The next prime is 31221251. The reversal of 31221228 is 82212213.

It is a happy number.

31221228 is nontrivially palindromic in base 5.

It is not an unprimeable number, because it can be changed into a prime (31221227) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 18550 + ... + 20162.

Almost surely, 2^31221228 is an apocalyptic number.

It is an amenable number.

31221228 is an abundant number, since it is smaller than the sum of its proper divisors (41673496).

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

31221228 is an equidigital number, since it uses as much as digits as its factorization.

31221228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3233 (or 1618 counting only the distinct ones).

The product of its digits is 384, while the sum is 21.

The square root of 31221228 is about 5587.5959052172. The cubic root of 31221228 is about 314.8835649285.

The spelling of 31221228 in words is "thirty-one million, two hundred twenty-one thousand, two hundred twenty-eight".