505891 has 4 divisors (see below), whose sum is σ = 507384. Its totient is φ = 504400.

The previous prime is 505877. The next prime is 505907. The reversal of 505891 is 198505.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 505891 - 2⁷ = 505763 is a prime.

It is a Duffinian number.

505891 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (505811) 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, 36 + ... + 1006.

It is an arithmetic number, because the mean of its divisors is an integer number (126846).

2⁵⁰⁵⁸⁹¹ is an apocalyptic number.

505891 is a deficient number, since it is larger than the sum of its proper divisors (1493).

505891 is an equidigital number, since it uses as much as digits as its factorization.

505891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1492.

The product of its (nonzero) digits is 1800, while the sum is 28.

The square root of 505891 is about 711.2601493125. The cubic root of 505891 is about 79.6805490028.

The spelling of 505891 in words is "five hundred five thousand, eight hundred ninety-one".