31780117 has 2 divisors, whose sum is σ = 31780118. Its totient is φ = 31780116.

The previous prime is 31780087. The next prime is 31780127. The reversal of 31780117 is 71108713.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21288996 + 10491121 = 4614^2 + 3239^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31780117 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31780127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15890058 + 15890059.

It is an arithmetic number, because the mean of its divisors is an integer number (15890059).

Almost surely, 2^31780117 is an apocalyptic number.

It is an amenable number.

31780117 is a deficient number, since it is larger than the sum of its proper divisors (1).

31780117 is an equidigital number, since it uses as much as digits as its factorization.

31780117 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1176, while the sum is 28.

The square root of 31780117 is about 5637.3856529423. The cubic root of 31780117 is about 316.7513665705.

The spelling of 31780117 in words is "thirty-one million, seven hundred eighty thousand, one hundred seventeen".