78911986 has 4 divisors (see below), whose sum is σ = 118367982. Its totient is φ = 39455992.

The previous prime is 78911981. The next prime is 78911993. The reversal of 78911986 is 68911987.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 68911987 = 641 ⋅107507.

It can be written as a sum of positive squares in only one way, i.e., 78588225 + 323761 = 8865^2 + 569^2 .

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (78911981) 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 as a sum of consecutive naturals, namely, 19727995 + ... + 19727998.

Almost surely, 2^78911986 is an apocalyptic number.

78911986 is a deficient number, since it is larger than the sum of its proper divisors (39455996).

78911986 is a wasteful number, since it uses less digits than its factorization.

78911986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39455995.

The product of its digits is 217728, while the sum is 49.

The square root of 78911986 is about 8883.2418631939. The cubic root of 78911986 is about 428.9246357978.

Subtracting from 78911986 its reverse (68911987), we obtain a palindrome (9999999).

It can be divided in two parts, 78911 and 986, that added together give a palindrome (79897).

The spelling of 78911986 in words is "seventy-eight million, nine hundred eleven thousand, nine hundred eighty-six".