1261637912789 has 2 divisors, whose sum is σ = 1261637912790. Its totient is φ = 1261637912788.

The previous prime is 1261637912767. The next prime is 1261637912827. The reversal of 1261637912789 is 9872197361621.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1033018140625 + 228619772164 = 1016375^2 + 478142^2 .

It is a cyclic number.

It is not a de Polignac number, because 1261637912789 - 2⁸ = 1261637912533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1261637912729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 630818956394 + 630818956395.

It is an arithmetic number, because the mean of its divisors is an integer number (630818956395).

Almost surely, 2^{1261637912789} is an apocalyptic number.

It is an amenable number.

1261637912789 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261637912789 is an equidigital number, since it uses as much as digits as its factorization.

1261637912789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13716864, while the sum is 62.

The spelling of 1261637912789 in words is "one trillion, two hundred sixty-one billion, six hundred thirty-seven million, nine hundred twelve thousand, seven hundred eighty-nine".