3720221 has 4 divisors (see below), whose sum is σ = 3733212. Its totient is φ = 3707232.

The previous prime is 3720209. The next prime is 3720247. The reversal of 3720221 is 1220273.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1220273 = 977 ⋅1249.

It can be written as a sum of positive squares in 2 ways, for example, as 2292196 + 1428025 = 1514^2 + 1195^2 .

It is a cyclic number.

It is not a de Polignac number, because 3720221 - 2¹⁰ = 3719197 is a prime.

It is an Ulam number.

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 3720221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3720251) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6056 + ... + 6641.

It is an arithmetic number, because the mean of its divisors is an integer number (933303).

Almost surely, 2^3720221 is an apocalyptic number.

It is an amenable number.

3720221 is a deficient number, since it is larger than the sum of its proper divisors (12991).

3720221 is a wasteful number, since it uses less digits than its factorization.

3720221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12990.

The product of its (nonzero) digits is 168, while the sum is 17.

The square root of 3720221 is about 1928.7874429288. The cubic root of 3720221 is about 154.9492862186.

Adding to 3720221 its reverse (1220273), we get a palindrome (4940494).

The spelling of 3720221 in words is "three million, seven hundred twenty thousand, two hundred twenty-one".