12561065581 has 8 divisors (see below), whose sum is σ = 12626705664. Its totient is φ = 12495574560.

The previous prime is 12561065563. The next prime is 12561065591. The reversal of 12561065581 is 18556016521.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12561065581 is a prime.

It is a super-2 number, since 2×12561065581² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12561065591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 133746 + ... + 207388.

It is an arithmetic number, because the mean of its divisors is an integer number (1578338208).

Almost surely, 2^12561065581 is an apocalyptic number.

It is an amenable number.

12561065581 is a deficient number, since it is larger than the sum of its proper divisors (65640083).

12561065581 is an equidigital number, since it uses as much as digits as its factorization.

12561065581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74531.

The product of its (nonzero) digits is 72000, while the sum is 40.

It can be divided in two parts, 125610 and 65581, that added together give a palindrome (191191).

The spelling of 12561065581 in words is "twelve billion, five hundred sixty-one million, sixty-five thousand, five hundred eighty-one".