31981168023157 has 2 divisors, whose sum is σ = 31981168023158. Its totient is φ = 31981168023156.

The previous prime is 31981168023053. The next prime is 31981168023191. The reversal of 31981168023157 is 75132086118913.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 28779265766161 + 3201902256996 = 5364631^2 + 1789386^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31981168023157 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 31981168023098 and 31981168023107.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31981168023757) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15990584011578 + 15990584011579.

It is an arithmetic number, because the mean of its divisors is an integer number (15990584011579).

Almost surely, 2^{31981168023157} is an apocalyptic number.

It is an amenable number.

31981168023157 is a deficient number, since it is larger than the sum of its proper divisors (1).

31981168023157 is an equidigital number, since it uses as much as digits as its factorization.

31981168023157 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2177280, while the sum is 55.

The spelling of 31981168023157 in words is "thirty-one trillion, nine hundred eighty-one billion, one hundred sixty-eight million, twenty-three thousand, one hundred fifty-seven".