3959991 has 24 divisors (see below), whose sum is σ = 6589440. Its totient is φ = 2244816.

The previous prime is 3959983. The next prime is 3960007. The reversal of 3959991 is 1999593.

It is not a de Polignac number, because 3959991 - 2³ = 3959983 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3959911) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 14926 + ... + 15188.

It is an arithmetic number, because the mean of its divisors is an integer number (274560).

Almost surely, 2^3959991 is an apocalyptic number.

3959991 is a deficient number, since it is larger than the sum of its proper divisors (2629449).

3959991 is a wasteful number, since it uses less digits than its factorization.

3959991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 515 (or 512 counting only the distinct ones).

The product of its digits is 98415, while the sum is 45.

The square root of 3959991 is about 1989.9726128769. The cubic root of 3959991 is about 158.2090780138.

It can be divided in two parts, 3959 and 991, that added together give a triangular number (4950 = T₉₉).

The spelling of 3959991 in words is "three million, nine hundred fifty-nine thousand, nine hundred ninety-one".