78786891 has 48 divisors (see below), whose sum is σ = 129676800. Its totient is φ = 47177856.

The previous prime is 78786887. The next prime is 78786907. The reversal of 78786891 is 19868787.

It is not a de Polignac number, because 78786891 - 2² = 78786887 is a prime.

It is not an unprimeable number, because it can be changed into a prime (78786391) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 179250 + ... + 179688.

It is an arithmetic number, because the mean of its divisors is an integer number (2701600).

Almost surely, 2^78786891 is an apocalyptic number.

78786891 is a deficient number, since it is larger than the sum of its proper divisors (50889909).

78786891 is a wasteful number, since it uses less digits than its factorization.

78786891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 505 (or 482 counting only the distinct ones).

The product of its digits is 1354752, while the sum is 54.

The square root of 78786891 is about 8876.1980036500. The cubic root of 78786891 is about 428.6978654093.

It can be divided in two parts, 787 and 86891, that added together give a palindrome (87678).

The spelling of 78786891 in words is "seventy-eight million, seven hundred eighty-six thousand, eight hundred ninety-one".