12778765 has 4 divisors (see below), whose sum is σ = 15334524. Its totient is φ = 10223008.

The previous prime is 12778741. The next prime is 12778769. The reversal of 12778765 is 56787721.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2653641 + 10125124 = 1629^2 + 3182^2 .

It is a cyclic number.

It is not a de Polignac number, because 12778765 - 2⁷ = 12778637 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 (12778769) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1277872 + ... + 1277881.

It is an arithmetic number, because the mean of its divisors is an integer number (3833631).

Almost surely, 2^12778765 is an apocalyptic number.

It is an amenable number.

12778765 is a deficient number, since it is larger than the sum of its proper divisors (2555759).

12778765 is an equidigital number, since it uses as much as digits as its factorization.

12778765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2555758.

The product of its digits is 164640, while the sum is 43.

The square root of 12778765 is about 3574.7398506745. The cubic root of 12778765 is about 233.7919901307.

The spelling of 12778765 in words is "twelve million, seven hundred seventy-eight thousand, seven hundred sixty-five".