78919191 has 40 divisors (see below), whose sum is σ = 128066400. Its totient is φ = 48143808.

The previous prime is 78919189. The next prime is 78919193. The reversal of 78919191 is 19191987.

It is an interprime number because it is at equal distance from previous prime (78919189) and next prime (78919193).

It is not a de Polignac number, because 78919191 - 2¹ = 78919189 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78919193) 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 39 ways as a sum of consecutive naturals, for example, 156646 + ... + 157148.

It is an arithmetic number, because the mean of its divisors is an integer number (3201660).

Almost surely, 2^78919191 is an apocalyptic number.

78919191 is a deficient number, since it is larger than the sum of its proper divisors (49147209).

78919191 is a wasteful number, since it uses less digits than its factorization.

78919191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 677 (or 668 counting only the distinct ones).

The product of its digits is 40824, while the sum is 45.

The square root of 78919191 is about 8883.6473928224. The cubic root of 78919191 is about 428.9376896151.

It can be divided in two parts, 7 and 8919191, that added together give a palindrome (8919198).

The spelling of 78919191 in words is "seventy-eight million, nine hundred nineteen thousand, one hundred ninety-one".