263821 has 2 divisors, whose sum is σ = 263822. Its totient is φ = 263820.

The previous prime is 263819. The next prime is 263827. The reversal of 263821 is 128362.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 260100 + 3721 = 510^2 + 61^2 .

It is a cyclic number.

It is not a de Polignac number, because 263821 - 2¹ = 263819 is a prime.

Together with 263819, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 263792 and 263801.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (263827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 131910 + 131911.

It is an arithmetic number, because the mean of its divisors is an integer number (131911).

2²⁶³⁸²¹ is an apocalyptic number.

It is an amenable number.

263821 is a deficient number, since it is larger than the sum of its proper divisors (1).

263821 is an equidigital number, since it uses as much as digits as its factorization.

263821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 576, while the sum is 22.

The square root of 263821 is about 513.6350844715. The cubic root of 263821 is about 64.1361846187.

The spelling of 263821 in words is "two hundred sixty-three thousand, eight hundred twenty-one".