1312845661 has 4 divisors (see below), whose sum is σ = 1312922524. Its totient is φ = 1312768800.

The previous prime is 1312845643. The next prime is 1312845683. The reversal of 1312845661 is 1665482131.

It is a happy number.

1312845661 is a nontrivial binomial coefficient, being equal to C(51242, 2).

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 377097561 + 935748100 = 19419^2 + 30590^2 .

It is a 3-Lehmer number, since φ(1312845661) divides (1312845661-1)³.

It is a cyclic number.

It is not a de Polignac number, because 1312845661 - 2²³ = 1304457053 is a prime.

It is a deceptive number, since it divides R_1312845660.

It is a self number, because there is not a number n which added to its sum of digits gives 1312845661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1312845601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1 + ... + 51241.

It is an arithmetic number, because the mean of its divisors is an integer number (328230631).

It is a Poulet number, since it divides 2^1312845660-1.

Almost surely, 2^1312845661 is an apocalyptic number.

1312845661 is the 51241-st triangular number and also the 25621-st hexagonal number.

1312845661 is the 17081-st centered nonagonal number.

It is an amenable number.

1312845661 is a deficient number, since it is larger than the sum of its proper divisors (76863).

1312845661 is an equidigital number, since it uses as much as digits as its factorization.

1312845661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76862.

The product of its digits is 34560, while the sum is 37.

The square root of 1312845661 is about 36233.2121264455. The cubic root of 1312845661 is about 1094.9758926603.

The spelling of 1312845661 in words is "one billion, three hundred twelve million, eight hundred forty-five thousand, six hundred sixty-one".