31218009 has 4 divisors (see below), whose sum is σ = 41624016. Its totient is φ = 20812004.

The previous prime is 31217987. The next prime is 31218017. The reversal of 31218009 is 90081213.

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.

It is a cyclic number.

It is not a de Polignac number, because 31218009 - 2⁹ = 31217497 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31218009.

It is not an unprimeable number, because it can be changed into a prime (31218049) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5202999 + ... + 5203004.

It is an arithmetic number, because the mean of its divisors is an integer number (10406004).

Almost surely, 2^31218009 is an apocalyptic number.

It is an amenable number.

31218009 is a deficient number, since it is larger than the sum of its proper divisors (10406007).

31218009 is a wasteful number, since it uses less digits than its factorization.

31218009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10406006.

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 31218009 is about 5587.3078490450. The cubic root of 31218009 is about 314.8727427508.

The spelling of 31218009 in words is "thirty-one million, two hundred eighteen thousand, nine".