31381717 has 2 divisors, whose sum is σ = 31381718. Its totient is φ = 31381716.

The previous prime is 31381699. The next prime is 31381739. The reversal of 31381717 is 71718313.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 26946481 + 4435236 = 5191^2 + 2106^2 .

It is an emirp because it is prime and its reverse (71718313) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31381717 - 2²³ = 22993109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31381747) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15690858 + 15690859.

It is an arithmetic number, because the mean of its divisors is an integer number (15690859).

Almost surely, 2^31381717 is an apocalyptic number.

It is an amenable number.

31381717 is a deficient number, since it is larger than the sum of its proper divisors (1).

31381717 is an equidigital number, since it uses as much as digits as its factorization.

31381717 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3528, while the sum is 31.

The square root of 31381717 is about 5601.9386822778. The cubic root of 31381717 is about 315.4221835523.

The spelling of 31381717 in words is "thirty-one million, three hundred eighty-one thousand, seven hundred seventeen".