1261371387391 has 2 divisors, whose sum is σ = 1261371387392. Its totient is φ = 1261371387390.

The previous prime is 1261371387343. The next prime is 1261371387443. The reversal of 1261371387391 is 1937831731621.

It is an a-pointer prime, because the next prime (1261371387443) can be obtained adding 1261371387391 to its sum of digits (52).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1261371387391 - 2¹⁷ = 1261371256319 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1261371387091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 630685693695 + 630685693696.

It is an arithmetic number, because the mean of its divisors is an integer number (630685693696).

Almost surely, 2^{1261371387391} is an apocalyptic number.

1261371387391 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261371387391 is an equidigital number, since it uses as much as digits as its factorization.

1261371387391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1143072, while the sum is 52.

The spelling of 1261371387391 in words is "one trillion, two hundred sixty-one billion, three hundred seventy-one million, three hundred eighty-seven thousand, three hundred ninety-one".