31397 has 2 divisors, whose sum is σ = 31398. Its totient is φ = 31396.

The previous prime is 31393. The next prime is 31469. The reversal of 31397 is 79313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25921 + 5476 = 161^2 + 74^2 .

It is a cyclic number.

It is not a de Polignac number, because 31397 - 2² = 31393 is a prime.

It is a Chen prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 31397.

It is not a weakly prime, because it can be changed into another prime (31391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15698 + 15699.

It is an arithmetic number, because the mean of its divisors is an integer number (15699).

2³¹³⁹⁷ is an apocalyptic number.

It is an amenable number.

31397 is a deficient number, since it is larger than the sum of its proper divisors (1).

31397 is an equidigital number, since it uses as much as digits as its factorization.

31397 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 567, while the sum is 23.

The square root of 31397 is about 177.1919862748. The cubic root of 31397 is about 31.5473379125.

The spelling of 31397 in words is "thirty-one thousand, three hundred ninety-seven".