1261859359665 has 16 divisors (see below), whose sum is σ = 2019025512000. Its totient is φ = 672974812992.

The previous prime is 1261859359613. The next prime is 1261859359681. The reversal of 1261859359665 is 5669539581621.

It is not a de Polignac number, because 1261859359665 - 2¹² = 1261859355569 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1261859359596 and 1261859359605.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 421390 + ... + 1643559.

It is an arithmetic number, because the mean of its divisors is an integer number (126189094500).

Almost surely, 2^{1261859359665} is an apocalyptic number.

1261859359665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1261859359665 is a deficient number, since it is larger than the sum of its proper divisors (757166152335).

1261859359665 is a wasteful number, since it uses less digits than its factorization.

1261859359665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2105696.

The product of its digits is 104976000, while the sum is 66.

The spelling of 1261859359665 in words is "one trillion, two hundred sixty-one billion, eight hundred fifty-nine million, three hundred fifty-nine thousand, six hundred sixty-five".