2865991 has 4 divisors (see below), whose sum is σ = 2871000. Its totient is φ = 2860984.

The previous prime is 2865977. The next prime is 2866001. The reversal of 2865991 is 1995682.

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 2865991 - 2⁹ = 2865479 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 an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2865901) 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, 1516 + ... + 2833.

It is an arithmetic number, because the mean of its divisors is an integer number (717750).

2^2865991 is an apocalyptic number.

2865991 is a deficient number, since it is larger than the sum of its proper divisors (5009).

2865991 is an equidigital number, since it uses as much as digits as its factorization.

2865991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5008.

The product of its digits is 38880, while the sum is 40.

The square root of 2865991 is about 1692.9238021837. The cubic root of 2865991 is about 142.0446695412.

The spelling of 2865991 in words is "two million, eight hundred sixty-five thousand, nine hundred ninety-one".