3688821 has 10 divisors (see below), whose sum is σ = 5510582. Its totient is φ = 2459160.

The previous prime is 3688801. The next prime is 3688837. The reversal of 3688821 is 1288863.

3688821 = T₃₈ + T₃₉ + ... + T₂₈₀.

3688821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 2340900 + 1347921 = 1530^2 + 1161^2 .

It is not a de Polignac number, because 3688821 - 2⁶ = 3688757 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3688801) 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 9 ways as a sum of consecutive naturals, for example, 22690 + ... + 22851.

Almost surely, 2^3688821 is an apocalyptic number.

It is an amenable number.

3688821 is a deficient number, since it is larger than the sum of its proper divisors (1821761).

3688821 is an equidigital number, since it uses as much as digits as its factorization.

3688821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45553 (or 45544 counting only the distinct ones).

The product of its digits is 18432, while the sum is 36.

The square root of 3688821 is about 1920.6303652707. The cubic root of 3688821 is about 154.5121114080.

The spelling of 3688821 in words is "three million, six hundred eighty-eight thousand, eight hundred twenty-one".