1261637912729 has 2 divisors, whose sum is σ = 1261637912730. Its totient is φ = 1261637912728.

The previous prime is 1261637912681. The next prime is 1261637912747. The reversal of 1261637912729 is 9272197361621.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1236483952729 + 25153960000 = 1111973^2 + 158600^2 .

It is a cyclic number.

It is not a de Polignac number, because 1261637912729 - 2¹² = 1261637908633 is a prime.

It is not a weakly prime, because it can be changed into another prime (1261637912789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 630818956364 + 630818956365.

It is an arithmetic number, because the mean of its divisors is an integer number (630818956365).

Almost surely, 2^{1261637912729} is an apocalyptic number.

It is an amenable number.

1261637912729 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261637912729 is an equidigital number, since it uses as much as digits as its factorization.

1261637912729 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3429216, while the sum is 56.

The spelling of 1261637912729 in words is "one trillion, two hundred sixty-one billion, six hundred thirty-seven million, nine hundred twelve thousand, seven hundred twenty-nine".