31908397 has 2 divisors, whose sum is σ = 31908398. Its totient is φ = 31908396.

The previous prime is 31908379. The next prime is 31908403. The reversal of 31908397 is 79380913.

Together with previous prime (31908379) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 31036041 + 872356 = 5571^2 + 934^2 .

It is a cyclic number.

It is not a de Polignac number, because 31908397 - 2¹¹ = 31906349 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31908367) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15954198 + 15954199.

It is an arithmetic number, because the mean of its divisors is an integer number (15954199).

Almost surely, 2^31908397 is an apocalyptic number.

It is an amenable number.

31908397 is a deficient number, since it is larger than the sum of its proper divisors (1).

31908397 is an equidigital number, since it uses as much as digits as its factorization.

31908397 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 40824, while the sum is 40.

The square root of 31908397 is about 5648.7518090283. The cubic root of 31908397 is about 317.1769819140.

The spelling of 31908397 in words is "thirty-one million, nine hundred eight thousand, three hundred ninety-seven".