505821 has 8 divisors (see below), whose sum is σ = 679840. Its totient is φ = 334512.

The previous prime is 505819. The next prime is 505823. The reversal of 505821 is 128505.

It is an interprime number because it is at equal distance from previous prime (505819) and next prime (505823).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 505821 - 2¹ = 505819 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (505823) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 190 + ... + 1023.

It is an arithmetic number, because the mean of its divisors is an integer number (84980).

2⁵⁰⁵⁸²¹ is an apocalyptic number.

It is an amenable number.

505821 is a deficient number, since it is larger than the sum of its proper divisors (174019).

505821 is a wasteful number, since it uses less digits than its factorization.

505821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1355.

The product of its (nonzero) digits is 400, while the sum is 21.

The square root of 505821 is about 711.2109391735. The cubic root of 505821 is about 79.6768737080.

It can be divided in two parts, 505 and 821, that added together give a triangular number (1326 = T₅₁).

The spelling of 505821 in words is "five hundred five thousand, eight hundred twenty-one".