1261647879361 has 3 divisors (see below), whose sum is σ = 1261649002593. Its totient is φ = 1261646756130.

The previous prime is 1261647879337. The next prime is 1261647879419. The reversal of 1261647879361 is 1639787461621.

It is a happy number.

The square root of 1261647879361 is 1123231.

It is a perfect power (a square), and thus also a powerful number.

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 is not a de Polignac number, because 1261647879361 - 2²³ = 1261639490753 is a prime.

It is a super-2 number, since 2×1261647879361² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1261647879361.

It is not an unprimeable number, because it can be changed into a prime (1261647879301) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 561616 + ... + 1684846.

It is an arithmetic number, because the mean of its divisors is an integer number (420549667531).

Almost surely, 2^{1261647879361} is an apocalyptic number.

1261647879361 is the 1123231-st square number.

1261647879361 is the 561616-th centered octagonal number.

It is an amenable number.

1261647879361 is a deficient number, since it is larger than the sum of its proper divisors (1123232).

1261647879361 is an frugal number, since it uses more digits than its factorization.

1261647879361 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2246462 (or 1123231 counting only the distinct ones).

The product of its digits is 18289152, while the sum is 61.

The spelling of 1261647879361 in words is "one trillion, two hundred sixty-one billion, six hundred forty-seven million, eight hundred seventy-nine thousand, three hundred sixty-one".