12561973665 has 8 divisors (see below), whose sum is σ = 20099157888. Its totient is φ = 6699719280.

The previous prime is 12561973643. The next prime is 12561973679. The reversal of 12561973665 is 56637916521.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 12561973665 - 2⁹ = 12561973153 is a prime.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 418732441 + ... + 418732470.

It is an arithmetic number, because the mean of its divisors is an integer number (2512394736).

Almost surely, 2^12561973665 is an apocalyptic number.

12561973665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

12561973665 is a deficient number, since it is larger than the sum of its proper divisors (7537184223).

12561973665 is an equidigital number, since it uses as much as digits as its factorization.

12561973665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 837464919.

The product of its digits is 2041200, while the sum is 51.

The spelling of 12561973665 in words is "twelve billion, five hundred sixty-one million, nine hundred seventy-three thousand, six hundred sixty-five".