3871921 has 2 divisors, whose sum is σ = 3871922. Its totient is φ = 3871920.

The previous prime is 3871919. The next prime is 3871961. The reversal of 3871921 is 1291783.

3871921 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3381921 + 490000 = 1839^2 + 700^2 .

It is an emirp because it is prime and its reverse (1291783) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3871921 - 2¹ = 3871919 is a prime.

Together with 3871919, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (3871961) 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 as a sum of consecutive naturals, namely, 1935960 + 1935961.

It is an arithmetic number, because the mean of its divisors is an integer number (1935961).

Almost surely, 2^3871921 is an apocalyptic number.

It is an amenable number.

3871921 is a deficient number, since it is larger than the sum of its proper divisors (1).

3871921 is an equidigital number, since it uses as much as digits as its factorization.

3871921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3024, while the sum is 31.

The square root of 3871921 is about 1967.7197463054. The cubic root of 3871921 is about 157.0274202584.

The spelling of 3871921 in words is "three million, eight hundred seventy-one thousand, nine hundred twenty-one".