1261818835129 has 2 divisors, whose sum is σ = 1261818835130. Its totient is φ = 1261818835128.

The previous prime is 1261818835049. The next prime is 1261818835159. The reversal of 1261818835129 is 9215388181621.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1091784663225 + 170034171904 = 1044885^2 + 412352^2 .

It is a cyclic number.

It is not a de Polignac number, because 1261818835129 - 2¹¹ = 1261818833081 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1261818835129.

It is not a weakly prime, because it can be changed into another prime (1261818835159) 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, 630909417564 + 630909417565.

It is an arithmetic number, because the mean of its divisors is an integer number (630909417565).

Almost surely, 2^{1261818835129} is an apocalyptic number.

It is an amenable number.

1261818835129 is a deficient number, since it is larger than the sum of its proper divisors (1).

1261818835129 is an equidigital number, since it uses as much as digits as its factorization.

1261818835129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1658880, while the sum is 55.

The spelling of 1261818835129 in words is "one trillion, two hundred sixty-one billion, eight hundred eighteen million, eight hundred thirty-five thousand, one hundred twenty-nine".