78257191 has 2 divisors, whose sum is σ = 78257192. Its totient is φ = 78257190.

The previous prime is 78257177. The next prime is 78257197. The reversal of 78257191 is 19175287.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78257191 is a prime.

It is a super-2 number, since 2×78257191² = 12248375886420962, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78257197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39128595 + 39128596.

It is an arithmetic number, because the mean of its divisors is an integer number (39128596).

Almost surely, 2^78257191 is an apocalyptic number.

78257191 is a deficient number, since it is larger than the sum of its proper divisors (1).

78257191 is an equidigital number, since it uses as much as digits as its factorization.

78257191 is an evil number, because the sum of its binary digits is even.

The product of its digits is 35280, while the sum is 40.

The square root of 78257191 is about 8846.3094564909. The cubic root of 78257191 is about 427.7349637979.

The spelling of 78257191 in words is "seventy-eight million, two hundred fifty-seven thousand, one hundred ninety-one".