4085821 has 4 divisors (see below), whose sum is σ = 4092732. Its totient is φ = 4078912.

The previous prime is 4085819. The next prime is 4085827. The reversal of 4085821 is 1285804.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2842596 + 1243225 = 1686^2 + 1115^2 .

It is a cyclic number.

It is not a de Polignac number, because 4085821 - 2¹ = 4085819 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 4085821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4085827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2476 + ... + 3781.

It is an arithmetic number, because the mean of its divisors is an integer number (1023183).

Almost surely, 2^4085821 is an apocalyptic number.

It is an amenable number.

4085821 is a deficient number, since it is larger than the sum of its proper divisors (6911).

4085821 is an equidigital number, since it uses as much as digits as its factorization.

4085821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6910.

The product of its (nonzero) digits is 2560, while the sum is 28.

The square root of 4085821 is about 2021.3413863076. The cubic root of 4085821 is about 159.8673509944.

The spelling of 4085821 in words is "four million, eighty-five thousand, eight hundred twenty-one".