20003821 has 2 divisors, whose sum is σ = 20003822. Its totient is φ = 20003820.

The previous prime is 20003803. The next prime is 20003833. The reversal of 20003821 is 12830002.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12638025 + 7365796 = 3555^2 + 2714^2 .

It is a cyclic number.

It is not a de Polignac number, because 20003821 - 2⁷ = 20003693 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20003795 and 20003804.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20003801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10001910 + 10001911.

It is an arithmetic number, because the mean of its divisors is an integer number (10001911).

Almost surely, 2^20003821 is an apocalyptic number.

It is an amenable number.

20003821 is a deficient number, since it is larger than the sum of its proper divisors (1).

20003821 is an equidigital number, since it uses as much as digits as its factorization.

20003821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 20003821 is about 4472.5631353845. The cubic root of 20003821 is about 271.4590468749.

Adding to 20003821 its reverse (12830002), we get a palindrome (32833823).

The spelling of 20003821 in words is "twenty million, three thousand, eight hundred twenty-one".