1256171315251 has 2 divisors, whose sum is σ = 1256171315252. Its totient is φ = 1256171315250.

The previous prime is 1256171315171. The next prime is 1256171315291. The reversal of 1256171315251 is 1525131716521.

It is an a-pointer prime, because the next prime (1256171315291) can be obtained adding 1256171315251 to its sum of digits (40).

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1256171315251 is a prime.

It is not a weakly prime, because it can be changed into another prime (1256171315291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628085657625 + 628085657626.

It is an arithmetic number, because the mean of its divisors is an integer number (628085657626).

Almost surely, 2^{1256171315251} is an apocalyptic number.

1256171315251 is a deficient number, since it is larger than the sum of its proper divisors (1).

1256171315251 is an equidigital number, since it uses as much as digits as its factorization.

1256171315251 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 63000, while the sum is 40.

The spelling of 1256171315251 in words is "one trillion, two hundred fifty-six billion, one hundred seventy-one million, three hundred fifteen thousand, two hundred fifty-one".