31130221 has 2 divisors, whose sum is σ = 31130222. Its totient is φ = 31130220.

The previous prime is 31130171. The next prime is 31130233. The reversal of 31130221 is 12203113.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 24950025 + 6180196 = 4995^2 + 2486^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31130221 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31130251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15565110 + 15565111.

It is an arithmetic number, because the mean of its divisors is an integer number (15565111).

Almost surely, 2^31130221 is an apocalyptic number.

It is an amenable number.

31130221 is a deficient number, since it is larger than the sum of its proper divisors (1).

31130221 is an equidigital number, since it uses as much as digits as its factorization.

31130221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 31130221 is about 5579.4462986931. The cubic root of 31130221 is about 314.5773149890.

Adding to 31130221 its reverse (12203113), we get a palindrome (43333334).

The spelling of 31130221 in words is "thirty-one million, one hundred thirty thousand, two hundred twenty-one".