31316321 has 2 divisors, whose sum is σ = 31316322. Its totient is φ = 31316320.

The previous prime is 31316309. The next prime is 31316323. The reversal of 31316321 is 12361313.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 27415696 + 3900625 = 5236^2 + 1975^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31316321 is a prime.

Together with 31316323, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 31316293 and 31316302.

It is not a weakly prime, because it can be changed into another prime (31316323) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15658160 + 15658161.

It is an arithmetic number, because the mean of its divisors is an integer number (15658161).

Almost surely, 2^31316321 is an apocalyptic number.

It is an amenable number.

31316321 is a deficient number, since it is larger than the sum of its proper divisors (1).

31316321 is an equidigital number, since it uses as much as digits as its factorization.

31316321 is an odious number, because the sum of its binary digits is odd.

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

The square root of 31316321 is about 5596.0987303656. The cubic root of 31316321 is about 315.2029296250.

Adding to 31316321 its reverse (12361313), we get a palindrome (43677634).

The spelling of 31316321 in words is "thirty-one million, three hundred sixteen thousand, three hundred twenty-one".