1317805240781 has 2 divisors, whose sum is σ = 1317805240782. Its totient is φ = 1317805240780.

The previous prime is 1317805240757. The next prime is 1317805240789. The reversal of 1317805240781 is 1870425087131.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 778513287556 + 539291953225 = 882334^2 + 734365^2 .

It is an emirp because it is prime and its reverse (1870425087131) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1317805240781 - 2²² = 1317801046477 is a prime.

It is a super-2 number, since 2×1317805240781² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1317805240789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 658902620390 + 658902620391.

It is an arithmetic number, because the mean of its divisors is an integer number (658902620391).

Almost surely, 2^{1317805240781} is an apocalyptic number.

It is an amenable number.

1317805240781 is a deficient number, since it is larger than the sum of its proper divisors (1).

1317805240781 is an equidigital number, since it uses as much as digits as its factorization.

1317805240781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 376320, while the sum is 47.

The spelling of 1317805240781 in words is "one trillion, three hundred seventeen billion, eight hundred five million, two hundred forty thousand, seven hundred eighty-one".