31313509 has 2 divisors, whose sum is σ = 31313510. Its totient is φ = 31313508.

The previous prime is 31313489. The next prime is 31313531. The reversal of 31313509 is 90531313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16080100 + 15233409 = 4010^2 + 3903^2 .

It is a cyclic number.

It is not a de Polignac number, because 31313509 - 2¹¹ = 31311461 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31313549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15656754 + 15656755.

It is an arithmetic number, because the mean of its divisors is an integer number (15656755).

Almost surely, 2^31313509 is an apocalyptic number.

It is an amenable number.

31313509 is a deficient number, since it is larger than the sum of its proper divisors (1).

31313509 is an equidigital number, since it uses as much as digits as its factorization.

31313509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1215, while the sum is 25.

The square root of 31313509 is about 5595.8474782646. The cubic root of 31313509 is about 315.1934949582.

The spelling of 31313509 in words is "thirty-one million, three hundred thirteen thousand, five hundred nine".