4003821 has 6 divisors (see below), whose sum is σ = 5783310. Its totient is φ = 2669208.

The previous prime is 4003819. The next prime is 4003841. The reversal of 4003821 is 1283004.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 2975625 + 1028196 = 1725^2 + 1014^2 .

It is not a de Polignac number, because 4003821 - 2¹ = 4003819 is a prime.

4003821 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 4003794 and 4003803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4003841) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 222426 + ... + 222443.

It is an arithmetic number, because the mean of its divisors is an integer number (963885).

Almost surely, 2^4003821 is an apocalyptic number.

It is an amenable number.

4003821 is a deficient number, since it is larger than the sum of its proper divisors (1779489).

4003821 is a wasteful number, since it uses less digits than its factorization.

4003821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 444875 (or 444872 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 4003821 is about 2000.9550219833. The cubic root of 4003821 is about 158.7906346060.

Adding to 4003821 its reverse (1283004), we get a palindrome (5286825).

The spelling of 4003821 in words is "four million, three thousand, eight hundred twenty-one".