78243791 has 4 divisors (see below), whose sum is σ = 79018584. Its totient is φ = 77469000.

The previous prime is 78243757. The next prime is 78243839. The reversal of 78243791 is 19734287.

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 78243791 - 2¹⁰ = 78242767 is a prime.

It is a super-2 number, since 2×78243791² = 12244181660103362, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78243701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 387245 + ... + 387446.

It is an arithmetic number, because the mean of its divisors is an integer number (19754646).

Almost surely, 2^78243791 is an apocalyptic number.

78243791 is a deficient number, since it is larger than the sum of its proper divisors (774793).

78243791 is a wasteful number, since it uses less digits than its factorization.

78243791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 774792.

The product of its digits is 84672, while the sum is 41.

The square root of 78243791 is about 8845.5520460851. The cubic root of 78243791 is about 427.7105486798.

The spelling of 78243791 in words is "seventy-eight million, two hundred forty-three thousand, seven hundred ninety-one".