4023821 has 2 divisors, whose sum is σ = 4023822. Its totient is φ = 4023820.

The previous prime is 4023809. The next prime is 4023829. The reversal of 4023821 is 1283204.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3553225 + 470596 = 1885^2 + 686^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-4023821 is a prime.

It is a super-2 number, since 2×4023821² = 32382270880082, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 4023793 and 4023802.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (4023829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2011910 + 2011911.

It is an arithmetic number, because the mean of its divisors is an integer number (2011911).

Almost surely, 2^4023821 is an apocalyptic number.

It is an amenable number.

4023821 is a deficient number, since it is larger than the sum of its proper divisors (1).

4023821 is an equidigital number, since it uses as much as digits as its factorization.

4023821 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 4023821 is about 2005.9464100519. The cubic root of 4023821 is about 159.0545940711.

The spelling of 4023821 in words is "four million, twenty-three thousand, eight hundred twenty-one".