78867991 has 4 divisors (see below), whose sum is σ = 79866400. Its totient is φ = 77869584.

The previous prime is 78867983. The next prime is 78868043. The reversal of 78867991 is 19976887.

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

It is a cyclic number.

It is not a de Polignac number, because 78867991 - 2³ = 78867983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78867941) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 499086 + ... + 499243.

It is an arithmetic number, because the mean of its divisors is an integer number (19966600).

Almost surely, 2^78867991 is an apocalyptic number.

78867991 is a deficient number, since it is larger than the sum of its proper divisors (998409).

78867991 is an equidigital number, since it uses as much as digits as its factorization.

78867991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 998408.

The product of its digits is 1524096, while the sum is 55.

The square root of 78867991 is about 8880.7652260377. The cubic root of 78867991 is about 428.8449096442.

The spelling of 78867991 in words is "seventy-eight million, eight hundred sixty-seven thousand, nine hundred ninety-one".