3971221 has 4 divisors (see below), whose sum is σ = 3975244. Its totient is φ = 3967200.

The previous prime is 3971213. The next prime is 3971239. The reversal of 3971221 is 1221793.

3971221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 784996 + 3186225 = 886^2 + 1785^2 .

It is a cyclic number.

It is not a de Polignac number, because 3971221 - 2³ = 3971213 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 (3971281) 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 3 ways as a sum of consecutive naturals, for example, 601 + ... + 2881.

It is an arithmetic number, because the mean of its divisors is an integer number (993811).

Almost surely, 2^3971221 is an apocalyptic number.

It is an amenable number.

3971221 is a deficient number, since it is larger than the sum of its proper divisors (4023).

3971221 is a wasteful number, since it uses less digits than its factorization.

3971221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4022.

The product of its digits is 756, while the sum is 25.

The square root of 3971221 is about 1992.7922621287. The cubic root of 3971221 is about 158.3584900625.

The spelling of 3971221 in words is "three million, nine hundred seventy-one thousand, two hundred twenty-one".