31113209 has 4 divisors (see below), whose sum is σ = 31836816. Its totient is φ = 30389604.

The previous prime is 31113167. The next prime is 31113211. The reversal of 31113209 is 90231113.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 90231113 = 7 ⋅12890159.

It is a cyclic number.

It is not a de Polignac number, because 31113209 - 2⁸ = 31112953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (31113289) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 361739 + ... + 361824.

It is an arithmetic number, because the mean of its divisors is an integer number (7959204).

Almost surely, 2^31113209 is an apocalyptic number.

It is an amenable number.

31113209 is a deficient number, since it is larger than the sum of its proper divisors (723607).

31113209 is an equidigital number, since it uses as much as digits as its factorization.

31113209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 723606.

The product of its (nonzero) digits is 162, while the sum is 20.

The square root of 31113209 is about 5577.9215663184. The cubic root of 31113209 is about 314.5200012892.

The spelling of 31113209 in words is "thirty-one million, one hundred thirteen thousand, two hundred nine".