13638778 has 4 divisors (see below), whose sum is σ = 20458170. Its totient is φ = 6819388.

The previous prime is 13638763. The next prime is 13638799. The reversal of 13638778 is 87783631.

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., 13638249 + 529 = 3693^2 + 23^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3409693 + ... + 3409696.

Almost surely, 2^13638778 is an apocalyptic number.

13638778 is a deficient number, since it is larger than the sum of its proper divisors (6819392).

13638778 is an equidigital number, since it uses as much as digits as its factorization.

13638778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6819391.

The product of its digits is 169344, while the sum is 43.

The square root of 13638778 is about 3693.0716212930. The cubic root of 13638778 is about 238.9232902163.

The spelling of 13638778 in words is "thirteen million, six hundred thirty-eight thousand, seven hundred seventy-eight".