31230209 has 2 divisors, whose sum is σ = 31230210. Its totient is φ = 31230208.

The previous prime is 31230191. The next prime is 31230211. The reversal of 31230209 is 90203213.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27040000 + 4190209 = 5200^2 + 2047^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31230209 is a prime.

Together with 31230211, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31230229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15615104 + 15615105.

It is an arithmetic number, because the mean of its divisors is an integer number (15615105).

Almost surely, 2^31230209 is an apocalyptic number.

It is an amenable number.

31230209 is a deficient number, since it is larger than the sum of its proper divisors (1).

31230209 is an equidigital number, since it uses as much as digits as its factorization.

31230209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 324, while the sum is 20.

The square root of 31230209 is about 5588.3995025410. The cubic root of 31230209 is about 314.9137548384.

The spelling of 31230209 in words is "thirty-one million, two hundred thirty thousand, two hundred nine".