78705791 has 4 divisors (see below), whose sum is σ = 78724584. Its totient is φ = 78687000.

The previous prime is 78705779. The next prime is 78705811. The reversal of 78705791 is 19750787.

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 78705791 - 2¹⁰ = 78704767 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 (78705721) 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, 56 + ... + 12546.

It is an arithmetic number, because the mean of its divisors is an integer number (19681146).

Almost surely, 2^78705791 is an apocalyptic number.

78705791 is a deficient number, since it is larger than the sum of its proper divisors (18793).

78705791 is a wasteful number, since it uses less digits than its factorization.

78705791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18792.

The product of its (nonzero) digits is 123480, while the sum is 44.

The square root of 78705791 is about 8871.6284300009. The cubic root of 78705791 is about 428.5507202322.

The spelling of 78705791 in words is "seventy-eight million, seven hundred five thousand, seven hundred ninety-one".