31664209 has 2 divisors, whose sum is σ = 31664210. Its totient is φ = 31664208.

The previous prime is 31664197. The next prime is 31664221. The reversal of 31664209 is 90246613.

It is a balanced prime because it is at equal distance from previous prime (31664197) and next prime (31664221).

It can be written as a sum of positive squares in only one way, i.e., 17766225 + 13897984 = 4215^2 + 3728^2 .

It is an emirp because it is prime and its reverse (90246613) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31664209 - 2¹³ = 31656017 is a prime.

It is not a weakly prime, because it can be changed into another prime (31664239) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15832104 + 15832105.

It is an arithmetic number, because the mean of its divisors is an integer number (15832105).

Almost surely, 2^31664209 is an apocalyptic number.

It is an amenable number.

31664209 is a deficient number, since it is larger than the sum of its proper divisors (1).

31664209 is an equidigital number, since it uses as much as digits as its factorization.

31664209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 31664209 is about 5627.0959650605. The cubic root of 31664209 is about 316.3658137384.

The spelling of 31664209 in words is "thirty-one million, six hundred sixty-four thousand, two hundred nine".