919891 has 4 divisors (see below), whose sum is σ = 1051312. Its totient is φ = 788472.

The previous prime is 919883. The next prime is 919901. The reversal of 919891 is 198919.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 919891 - 2³ = 919883 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 919891.

It is not an unprimeable number, because it can be changed into a prime (919811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65700 + ... + 65713.

It is an arithmetic number, because the mean of its divisors is an integer number (262828).

2⁹¹⁹⁸⁹¹ is an apocalyptic number.

919891 is a deficient number, since it is larger than the sum of its proper divisors (131421).

919891 is a wasteful number, since it uses less digits than its factorization.

919891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131420.

The product of its digits is 5832, while the sum is 37.

The square root of 919891 is about 959.1094828016. The cubic root of 919891 is about 97.2550414491.

It can be divided in two parts, 9 and 19891, that added together give a triangular number (19900 = T₁₉₉).

The spelling of 919891 in words is "nine hundred nineteen thousand, eight hundred ninety-one".