31213009 has 2 divisors, whose sum is σ = 31213010. Its totient is φ = 31213008.

The previous prime is 31212899. The next prime is 31213027. The reversal of 31213009 is 90031213.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 24206400 + 7006609 = 4920^2 + 2647^2 .

It is an emirp because it is prime and its reverse (90031213) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31213009 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31213069) 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, 15606504 + 15606505.

It is an arithmetic number, because the mean of its divisors is an integer number (15606505).

Almost surely, 2^31213009 is an apocalyptic number.

It is an amenable number.

31213009 is a deficient number, since it is larger than the sum of its proper divisors (1).

31213009 is an equidigital number, since it uses as much as digits as its factorization.

31213009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 162, while the sum is 19.

The square root of 31213009 is about 5586.8603884472. The cubic root of 31213009 is about 314.8559314313.

The spelling of 31213009 in words is "thirty-one million, two hundred thirteen thousand, nine".