3939991 has 4 divisors (see below), whose sum is σ = 4298184. Its totient is φ = 3581800.

The previous prime is 3939989. The next prime is 3939997. The reversal of 3939991 is 1999393.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1999393 = 11 ⋅181763.

It is a cyclic number.

It is not a de Polignac number, because 3939991 - 2¹ = 3939989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3939997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 179080 + ... + 179101.

It is an arithmetic number, because the mean of its divisors is an integer number (1074546).

Almost surely, 2^3939991 is an apocalyptic number.

3939991 is a deficient number, since it is larger than the sum of its proper divisors (358193).

3939991 is a wasteful number, since it uses less digits than its factorization.

3939991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 358192.

The product of its digits is 59049, while the sum is 43.

The square root of 3939991 is about 1984.9410570594. The cubic root of 3939991 is about 157.9422825022.

The spelling of 3939991 in words is "three million, nine hundred thirty-nine thousand, nine hundred ninety-one".