3917921 has 4 divisors (see below), whose sum is σ = 4477632. Its totient is φ = 3358212.

The previous prime is 3917909. The next prime is 3917923. The reversal of 3917921 is 1297193.

It is a happy number.

3917921 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 Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 3917921 - 2¹⁰ = 3916897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3917923) 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, 279845 + ... + 279858.

It is an arithmetic number, because the mean of its divisors is an integer number (1119408).

Almost surely, 2^3917921 is an apocalyptic number.

It is an amenable number.

3917921 is a deficient number, since it is larger than the sum of its proper divisors (559711).

3917921 is an equidigital number, since it uses as much as digits as its factorization.

3917921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 559710.

The product of its digits is 3402, while the sum is 32.

The square root of 3917921 is about 1979.3738909059. The cubic root of 3917921 is about 157.6468236978.

The spelling of 3917921 in words is "three million, nine hundred seventeen thousand, nine hundred twenty-one".