825821 has 2 divisors, whose sum is σ = 825822. Its totient is φ = 825820.

The previous prime is 825791. The next prime is 825827. The reversal of 825821 is 128528.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 657721 + 168100 = 811^2 + 410^2 .

It is a cyclic number.

It is not a de Polignac number, because 825821 - 2¹⁴ = 809437 is a prime.

It is a Chen prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 825821.

It is not a weakly prime, because it can be changed into another prime (825827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 412910 + 412911.

It is an arithmetic number, because the mean of its divisors is an integer number (412911).

2⁸²⁵⁸²¹ is an apocalyptic number.

It is an amenable number.

825821 is a deficient number, since it is larger than the sum of its proper divisors (1).

825821 is an equidigital number, since it uses as much as digits as its factorization.

825821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1280, while the sum is 26.

The square root of 825821 is about 908.7469394722. The cubic root of 825821 is about 93.8199738335.

The spelling of 825821 in words is "eight hundred twenty-five thousand, eight hundred twenty-one".