3921921 has 6 divisors (see below), whose sum is σ = 5665010. Its totient is φ = 2614608.

The previous prime is 3921919. The next prime is 3921941. The reversal of 3921921 is 1291293.

It can be written as a sum of positive squares in only one way, i.e., 3920400 + 1521 = 1980^2 + 39^2 .

It is not a de Polignac number, because 3921921 - 2¹ = 3921919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3921941) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 217876 + ... + 217893.

It is a Proth number, since it is equal to 1915 ⋅ 2¹¹ + 1 and 1915 < 2¹¹.

Almost surely, 2^3921921 is an apocalyptic number.

It is an amenable number.

3921921 is a deficient number, since it is larger than the sum of its proper divisors (1743089).

3921921 is a wasteful number, since it uses less digits than its factorization.

3921921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 435775 (or 435772 counting only the distinct ones).

The product of its digits is 972, while the sum is 27.

The square root of 3921921 is about 1980.3840536623. The cubic root of 3921921 is about 157.7004552724.

The spelling of 3921921 in words is "three million, nine hundred twenty-one thousand, nine hundred twenty-one".