78808591 has 2 divisors, whose sum is σ = 78808592. Its totient is φ = 78808590.

The previous prime is 78808507. The next prime is 78808607. The reversal of 78808591 is 19580887.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78808591 - 2¹³ = 78800399 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78808501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39404295 + 39404296.

It is an arithmetic number, because the mean of its divisors is an integer number (39404296).

Almost surely, 2^78808591 is an apocalyptic number.

78808591 is a deficient number, since it is larger than the sum of its proper divisors (1).

78808591 is an equidigital number, since it uses as much as digits as its factorization.

78808591 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 161280, while the sum is 46.

The square root of 78808591 is about 8877.4202897013. The cubic root of 78808591 is about 428.7372200516.

It can be divided in two parts, 7880 and 8591, that added together give a triangular number (16471 = T₁₈₁).

The spelling of 78808591 in words is "seventy-eight million, eight hundred eight thousand, five hundred ninety-one".