78750391 has 2 divisors, whose sum is σ = 78750392. Its totient is φ = 78750390.

The previous prime is 78750389. The next prime is 78750403. The reversal of 78750391 is 19305787.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 78750391 - 2¹ = 78750389 is a prime.

Together with 78750389, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78750361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39375195 + 39375196.

It is an arithmetic number, because the mean of its divisors is an integer number (39375196).

Almost surely, 2^78750391 is an apocalyptic number.

78750391 is the 5613-rd centered pentagonal number.

78750391 is a deficient number, since it is larger than the sum of its proper divisors (1).

78750391 is an equidigital number, since it uses as much as digits as its factorization.

78750391 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 52920, while the sum is 40.

The square root of 78750391 is about 8874.1417049763. The cubic root of 78750391 is about 428.6316535100.

The spelling of 78750391 in words is "seventy-eight million, seven hundred fifty thousand, three hundred ninety-one".