78577391 has 2 divisors, whose sum is σ = 78577392. Its totient is φ = 78577390.

The previous prime is 78577351. The next prime is 78577393. The reversal of 78577391 is 19377587.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78577391 - 2¹⁰ = 78576367 is a prime.

Together with 78577393, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78577393) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39288695 + 39288696.

It is an arithmetic number, because the mean of its divisors is an integer number (39288696).

Almost surely, 2^78577391 is an apocalyptic number.

78577391 is a deficient number, since it is larger than the sum of its proper divisors (1).

78577391 is an equidigital number, since it uses as much as digits as its factorization.

78577391 is an evil number, because the sum of its binary digits is even.

The product of its digits is 370440, while the sum is 47.

The square root of 78577391 is about 8864.3889242294. The cubic root of 78577391 is about 428.3175486452.

The spelling of 78577391 in words is "seventy-eight million, five hundred seventy-seven thousand, three hundred ninety-one".