78866191 has 2 divisors, whose sum is σ = 78866192. Its totient is φ = 78866190.

The previous prime is 78866189. The next prime is 78866209. The reversal of 78866191 is 19166887.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 78866191 - 2¹ = 78866189 is a prime.

Together with 78866189, 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 (78866591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39433095 + 39433096.

It is an arithmetic number, because the mean of its divisors is an integer number (39433096).

Almost surely, 2^78866191 is an apocalyptic number.

78866191 is a deficient number, since it is larger than the sum of its proper divisors (1).

78866191 is an equidigital number, since it uses as much as digits as its factorization.

78866191 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145152, while the sum is 46.

The square root of 78866191 is about 8880.6638828412. The cubic root of 78866191 is about 428.8416471178.

The spelling of 78866191 in words is "seventy-eight million, eight hundred sixty-six thousand, one hundred ninety-one".