78671591 has 2 divisors, whose sum is σ = 78671592. Its totient is φ = 78671590.

The previous prime is 78671581. The next prime is 78671623. The reversal of 78671591 is 19517687.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 78671591 - 2²² = 74477287 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78671581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39335795 + 39335796.

It is an arithmetic number, because the mean of its divisors is an integer number (39335796).

Almost surely, 2^78671591 is an apocalyptic number.

78671591 is a deficient number, since it is larger than the sum of its proper divisors (1).

78671591 is an equidigital number, since it uses as much as digits as its factorization.

78671591 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 105840, while the sum is 44.

The square root of 78671591 is about 8869.7007277585. The cubic root of 78671591 is about 428.4886385741.

The spelling of 78671591 in words is "seventy-eight million, six hundred seventy-one thousand, five hundred ninety-one".