31224221 has 6 divisors (see below), whose sum is σ = 36322110. Its totient is φ = 26763576.

The previous prime is 31224209. The next prime is 31224229. The reversal of 31224221 is 12242213.

It can be written as a sum of positive squares in only one way, i.e., 26112100 + 5112121 = 5110^2 + 2261^2 .

It is a de Polignac number, because none of the positive numbers 2^k-31224221 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 31224221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31224229) 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, 318566 + ... + 318663.

It is an arithmetic number, because the mean of its divisors is an integer number (6053685).

Almost surely, 2^31224221 is an apocalyptic number.

It is an amenable number.

31224221 is a deficient number, since it is larger than the sum of its proper divisors (5097889).

31224221 is an equidigital number, since it uses as much as digits as its factorization.

31224221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 637243 (or 637236 counting only the distinct ones).

The product of its digits is 192, while the sum is 17.

The square root of 31224221 is about 5587.8637241794. The cubic root of 31224221 is about 314.8936266339.

Adding to 31224221 its reverse (12242213), we get a palindrome (43466434).

The spelling of 31224221 in words is "thirty-one million, two hundred twenty-four thousand, two hundred twenty-one".