3981809 has 6 divisors (see below), whose sum is σ = 4311846. Its totient is φ = 3675360.

The previous prime is 3981767. The next prime is 3981821. The reversal of 3981809 is 9081893.

It can be written as a sum of positive squares in 3 ways, for example, as 93025 + 3888784 = 305^2 + 1972^2 .

It is not a de Polignac number, because 3981809 - 2²⁰ = 2933233 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (3981839) 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, 11612 + ... + 11949.

It is an arithmetic number, because the mean of its divisors is an integer number (718641).

Almost surely, 2^3981809 is an apocalyptic number.

It is an amenable number.

3981809 is a deficient number, since it is larger than the sum of its proper divisors (330037).

3981809 is a wasteful number, since it uses less digits than its factorization.

3981809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23587 (or 23574 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 38.

The square root of 3981809 is about 1995.4470677019. The cubic root of 3981809 is about 158.4991027159.

The spelling of 3981809 in words is "three million, nine hundred eighty-one thousand, eight hundred nine".