3656221 has 4 divisors (see below), whose sum is σ = 3694012. Its totient is φ = 3618432.

The previous prime is 3656183. The next prime is 3656231. The reversal of 3656221 is 1226563.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1226563 = 13 ⋅94351.

It can be written as a sum of positive squares in 2 ways, for example, as 1060900 + 2595321 = 1030^2 + 1611^2 .

It is a cyclic number.

It is not a de Polignac number, because 3656221 - 2⁹ = 3655709 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 (3656231) 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, 18750 + ... + 18943.

It is an arithmetic number, because the mean of its divisors is an integer number (923503).

Almost surely, 2^3656221 is an apocalyptic number.

It is an amenable number.

3656221 is a deficient number, since it is larger than the sum of its proper divisors (37791).

3656221 is an equidigital number, since it uses as much as digits as its factorization.

3656221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37790.

The product of its digits is 2160, while the sum is 25.

The square root of 3656221 is about 1912.1247344250. The cubic root of 3656221 is about 154.0555963879.

The spelling of 3656221 in words is "three million, six hundred fifty-six thousand, two hundred twenty-one".