13666792778 has 4 divisors (see below), whose sum is σ = 20500189170. Its totient is φ = 6833396388.

The previous prime is 13666792771. The next prime is 13666792781. The reversal of 13666792778 is 87729766631.

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

It can be written as a sum of positive squares in only one way, i.e., 11577114409 + 2089678369 = 107597^2 + 45713^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 13666792778.

It is not an unprimeable number, because it can be changed into a prime (13666792771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3416698193 + ... + 3416698196.

Almost surely, 2^13666792778 is an apocalyptic number.

13666792778 is a deficient number, since it is larger than the sum of its proper divisors (6833396392).

13666792778 is an equidigital number, since it uses as much as digits as its factorization.

13666792778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6833396391.

The product of its digits is 32006016, while the sum is 62.

The spelling of 13666792778 in words is "thirteen billion, six hundred sixty-six million, seven hundred ninety-two thousand, seven hundred seventy-eight".