78727791 has 4 divisors (see below), whose sum is σ = 104970392. Its totient is φ = 52485192.

The previous prime is 78727777. The next prime is 78727801. The reversal of 78727791 is 19772787.

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

It is not a de Polignac number, because 78727791 - 2¹¹ = 78725743 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 78727791.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78727291) 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, 13121296 + ... + 13121301.

It is an arithmetic number, because the mean of its divisors is an integer number (26242598).

Almost surely, 2^78727791 is an apocalyptic number.

78727791 is a deficient number, since it is larger than the sum of its proper divisors (26242601).

78727791 is a wasteful number, since it uses less digits than its factorization.

78727791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26242600.

The product of its digits is 345744, while the sum is 48.

The square root of 78727791 is about 8872.8682510223. The cubic root of 78727791 is about 428.5906462970.

The spelling of 78727791 in words is "seventy-eight million, seven hundred twenty-seven thousand, seven hundred ninety-one".