12780665865 has 32 divisors (see below), whose sum is σ = 24786748800. Its totient is φ = 6196685760.

The previous prime is 12780665857. The next prime is 12780665873. The reversal of 12780665865 is 56856608721.

It is an interprime number because it is at equal distance from previous prime (12780665857) and next prime (12780665873).

It is not a de Polignac number, because 12780665865 - 2³ = 12780665857 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4301770 + ... + 4304739.

It is an arithmetic number, because the mean of its divisors is an integer number (774585900).

Almost surely, 2^12780665865 is an apocalyptic number.

12780665865 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

12780665865 is a deficient number, since it is larger than the sum of its proper divisors (12006082935).

12780665865 is a wasteful number, since it uses less digits than its factorization.

12780665865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8606534 (or 8606528 counting only the distinct ones).

The product of its (nonzero) digits is 4838400, while the sum is 54.

The spelling of 12780665865 in words is "twelve billion, seven hundred eighty million, six hundred sixty-five thousand, eight hundred sixty-five".