778891 has 4 divisors (see below), whose sum is σ = 785152. Its totient is φ = 772632.

The previous prime is 778879. The next prime is 778903. The reversal of 778891 is 198877.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 198877 = 7 ⋅28411.

It is an interprime number because it is at equal distance from previous prime (778879) and next prime (778903).

It is a cyclic number.

It is not a de Polignac number, because 778891 - 2⁷ = 778763 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (778831) 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 in 3 ways as a sum of consecutive naturals, for example, 2940 + ... + 3193.

It is an arithmetic number, because the mean of its divisors is an integer number (196288).

2⁷⁷⁸⁸⁹¹ is an apocalyptic number.

778891 is a deficient number, since it is larger than the sum of its proper divisors (6261).

778891 is a wasteful number, since it uses less digits than its factorization.

778891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6260.

The product of its digits is 28224, while the sum is 40.

The square root of 778891 is about 882.5480156909. The cubic root of 778891 is about 92.0079939494.

The spelling of 778891 in words is "seven hundred seventy-eight thousand, eight hundred ninety-one".