3981509 has 4 divisors (see below), whose sum is σ = 4550304. Its totient is φ = 3412716.

The previous prime is 3981503. The next prime is 3981517. The reversal of 3981509 is 9051893.

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, and also an emirpimes, since its reverse is a distinct semiprime: 9051893 = 193 ⋅46901.

It is a cyclic number.

It is not a de Polignac number, because 3981509 - 2⁸ = 3981253 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 (3981503) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 284387 + ... + 284400.

It is an arithmetic number, because the mean of its divisors is an integer number (1137576).

Almost surely, 2^3981509 is an apocalyptic number.

It is an amenable number.

3981509 is a deficient number, since it is larger than the sum of its proper divisors (568795).

3981509 is an equidigital number, since it uses as much as digits as its factorization.

3981509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 568794.

The product of its (nonzero) digits is 9720, while the sum is 35.

The square root of 3981509 is about 1995.3718951614. The cubic root of 3981509 is about 158.4951220357.

The spelling of 3981509 in words is "three million, nine hundred eighty-one thousand, five hundred nine".