1261335443665 has 12 divisors (see below), whose sum is σ = 1663711875252. Its totient is φ = 917334867680.

The previous prime is 1261335443659. The next prime is 1261335443713. The reversal of 1261335443665 is 5663445331621.

It can be written as a sum of positive squares in 2 ways, for example, as 976900954689 + 284434488976 = 988383^2 + 533324^2 .

It is not a de Polignac number, because 1261335443665 - 2²⁹ = 1260798572753 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1042425382 + ... + 1042426591.

It is an arithmetic number, because the mean of its divisors is an integer number (138642656271).

Almost surely, 2^{1261335443665} is an apocalyptic number.

It is an amenable number.

1261335443665 is a deficient number, since it is larger than the sum of its proper divisors (402376431587).

1261335443665 is a wasteful number, since it uses less digits than its factorization.

1261335443665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2084852000 (or 2084851989 counting only the distinct ones).

The product of its digits is 4665600, while the sum is 49.

The spelling of 1261335443665 in words is "one trillion, two hundred sixty-one billion, three hundred thirty-five million, four hundred forty-three thousand, six hundred sixty-five".