12781720991 has 8 divisors (see below), whose sum is σ = 14024646720. Its totient is φ = 11575897632.

The previous prime is 12781720979. The next prime is 12781720999. The reversal of 12781720991 is 19902718721.

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

It is not a de Polignac number, because 12781720991 - 2³⁰ = 11707979167 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12781720999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9274871 + ... + 9276248.

It is an arithmetic number, because the mean of its divisors is an integer number (1753080840).

Almost surely, 2^12781720991 is an apocalyptic number.

12781720991 is a deficient number, since it is larger than the sum of its proper divisors (1242925729).

12781720991 is a wasteful number, since it uses less digits than its factorization.

12781720991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18551185.

The product of its (nonzero) digits is 127008, while the sum is 47.

The spelling of 12781720991 in words is "twelve billion, seven hundred eighty-one million, seven hundred twenty thousand, nine hundred ninety-one".