78286891 has 2 divisors, whose sum is σ = 78286892. Its totient is φ = 78286890.

The previous prime is 78286849. The next prime is 78286909. The reversal of 78286891 is 19868287.

It is a strong prime.

It is an emirp because it is prime and its reverse (19868287) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78286891 - 2⁷ = 78286763 is a prime.

It is a super-2 number, since 2×78286891² = 12257674604891762, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (78286841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39143445 + 39143446.

It is an arithmetic number, because the mean of its divisors is an integer number (39143446).

Almost surely, 2^78286891 is an apocalyptic number.

78286891 is a deficient number, since it is larger than the sum of its proper divisors (1).

78286891 is an equidigital number, since it uses as much as digits as its factorization.

78286891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 387072, while the sum is 49.

The square root of 78286891 is about 8847.9879633734. The cubic root of 78286891 is about 427.7890679704.

The spelling of 78286891 in words is "seventy-eight million, two hundred eighty-six thousand, eight hundred ninety-one".