4089991 has 4 divisors (see below), whose sum is σ = 4139352. Its totient is φ = 4040632.

The previous prime is 4089973. The next prime is 4090001. The reversal of 4089991 is 1999804.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 4089991 - 2¹³ = 4081799 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

4089991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4089191) 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, 24556 + ... + 24721.

It is an arithmetic number, because the mean of its divisors is an integer number (1034838).

Almost surely, 2^4089991 is an apocalyptic number.

4089991 is a deficient number, since it is larger than the sum of its proper divisors (49361).

4089991 is an equidigital number, since it uses as much as digits as its factorization.

4089991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49360.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 4089991 is about 2022.3726165077. The cubic root of 4089991 is about 159.9217195198.

The spelling of 4089991 in words is "four million, eighty-nine thousand, nine hundred ninety-one".