1256443959391 has 2 divisors, whose sum is σ = 1256443959392. Its totient is φ = 1256443959390.

The previous prime is 1256443959389. The next prime is 1256443959437. The reversal of 1256443959391 is 1939593446521.

It is a weak prime.

It is an emirp because it is prime and its reverse (1939593446521) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1256443959391 - 2¹ = 1256443959389 is a prime.

Together with 1256443959389, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1256443959361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 628221979695 + 628221979696.

It is an arithmetic number, because the mean of its divisors is an integer number (628221979696).

Almost surely, 2^{1256443959391} is an apocalyptic number.

1256443959391 is a deficient number, since it is larger than the sum of its proper divisors (1).

1256443959391 is an equidigital number, since it uses as much as digits as its factorization.

1256443959391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31492800, while the sum is 61.

The spelling of 1256443959391 in words is "one trillion, two hundred fifty-six billion, four hundred forty-three million, nine hundred fifty-nine thousand, three hundred ninety-one".