78191291 has 2 divisors, whose sum is σ = 78191292. Its totient is φ = 78191290.

The previous prime is 78191257. The next prime is 78191293. The reversal of 78191291 is 19219187.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78191291 - 2²² = 73996987 is a prime.

It is a super-2 number, since 2×78191291² = 12227755976493362, which contains 22 as substring.

Together with 78191293, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (78191293) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39095645 + 39095646.

It is an arithmetic number, because the mean of its divisors is an integer number (39095646).

Almost surely, 2^78191291 is an apocalyptic number.

78191291 is a deficient number, since it is larger than the sum of its proper divisors (1).

78191291 is an equidigital number, since it uses as much as digits as its factorization.

78191291 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9072, while the sum is 38.

The square root of 78191291 is about 8842.5839549308. The cubic root of 78191291 is about 427.6148655692.

The spelling of 78191291 in words is "seventy-eight million, one hundred ninety-one thousand, two hundred ninety-one".