78587891 has 2 divisors, whose sum is σ = 78587892. Its totient is φ = 78587890.

The previous prime is 78587813. The next prime is 78587893. The reversal of 78587891 is 19878587.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (19878587) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78587891 is a prime.

It is a super-2 number, since 2×78587891² = 12352113223655762, which contains 22 as substring.

Together with 78587893, it forms a pair of twin primes.

It is a Chen prime.

It is a zygodrome in base 6.

It is not a weakly prime, because it can be changed into another prime (78587893) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39293945 + 39293946.

It is an arithmetic number, because the mean of its divisors is an integer number (39293946).

Almost surely, 2^78587891 is an apocalyptic number.

78587891 is a deficient number, since it is larger than the sum of its proper divisors (1).

78587891 is an equidigital number, since it uses as much as digits as its factorization.

78587891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1128960, while the sum is 53.

The square root of 78587891 is about 8864.9811618525. The cubic root of 78587891 is about 428.3366259477.

The spelling of 78587891 in words is "seventy-eight million, five hundred eighty-seven thousand, eight hundred ninety-one".