4000821 has 16 divisors (see below), whose sum is σ = 5963328. Its totient is φ = 2364800.

The previous prime is 4000813. The next prime is 4000823. The reversal of 4000821 is 1280004.

4000821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 4000821 - 2³ = 4000813 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 4000821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4000823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 126 + ... + 2831.

It is an arithmetic number, because the mean of its divisors is an integer number (372708).

Almost surely, 2^4000821 is an apocalyptic number.

4000821 is a gapful number since it is divisible by the number (41) formed by its first and last digit.

It is an amenable number.

4000821 is a deficient number, since it is larger than the sum of its proper divisors (1962507).

4000821 is a wasteful number, since it uses less digits than its factorization.

4000821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3012.

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 4000821 is about 2000.2052394692. The cubic root of 4000821 is about 158.7509649227.

Adding to 4000821 its reverse (1280004), we get a palindrome (5280825).

The spelling of 4000821 in words is "four million, eight hundred twenty-one", and thus it is an aban number.