31138213 has 2 divisors, whose sum is σ = 31138214. Its totient is φ = 31138212.

The previous prime is 31138193. The next prime is 31138249. The reversal of 31138213 is 31283113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20268004 + 10870209 = 4502^2 + 3297^2 .

It is an emirp because it is prime and its reverse (31283113) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31138213 - 2⁵ = 31138181 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31138273) 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, 15569106 + 15569107.

It is an arithmetic number, because the mean of its divisors is an integer number (15569107).

Almost surely, 2^31138213 is an apocalyptic number.

It is an amenable number.

31138213 is a deficient number, since it is larger than the sum of its proper divisors (1).

31138213 is an equidigital number, since it uses as much as digits as its factorization.

31138213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 432, while the sum is 22.

The square root of 31138213 is about 5580.1624528324. The cubic root of 31138213 is about 314.6042329560.

The spelling of 31138213 in words is "thirty-one million, one hundred thirty-eight thousand, two hundred thirteen".