1802821 has 2 divisors, whose sum is σ = 1802822. Its totient is φ = 1802820.

The previous prime is 1802803. The next prime is 1802837. The reversal of 1802821 is 1282081.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1718721 + 84100 = 1311^2 + 290^2 .

It is an emirp because it is prime and its reverse (1282081) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1802821 - 2⁷ = 1802693 is a prime.

It is equal to p₁₃₅₂₆₅ and since 1802821 and 135265 have the same sum of digits, it is a Honaker prime.

It is a junction number, because it is equal to n+sod(n) for n = 1802792 and 1802801.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1802621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 901410 + 901411.

It is an arithmetic number, because the mean of its divisors is an integer number (901411).

2^1802821 is an apocalyptic number.

It is an amenable number.

1802821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1802821 is an equidigital number, since it uses as much as digits as its factorization.

1802821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 256, while the sum is 22.

The square root of 1802821 is about 1342.6916995349. The cubic root of 1802821 is about 121.7075544900.

The spelling of 1802821 in words is "one million, eight hundred two thousand, eight hundred twenty-one".