4320821 has 2 divisors, whose sum is σ = 4320822. Its totient is φ = 4320820.

The previous prime is 4320817. The next prime is 4320829. The reversal of 4320821 is 1280234.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3290596 + 1030225 = 1814^2 + 1015^2 .

It is a cyclic number.

It is not a de Polignac number, because 4320821 - 2² = 4320817 is a prime.

It is a super-2 number, since 2×4320821² = 37338988228082, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 4320793 and 4320802.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4320829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2160410 + 2160411.

It is an arithmetic number, because the mean of its divisors is an integer number (2160411).

Almost surely, 2^4320821 is an apocalyptic number.

It is an amenable number.

4320821 is a deficient number, since it is larger than the sum of its proper divisors (1).

4320821 is an equidigital number, since it uses as much as digits as its factorization.

4320821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 4320821 is about 2078.6584616045. The cubic root of 4320821 is about 162.8753736425.

The spelling of 4320821 in words is "four million, three hundred twenty thousand, eight hundred twenty-one".