42165991 has 4 divisors (see below), whose sum is σ = 48189712. Its totient is φ = 36142272.

The previous prime is 42165989. The next prime is 42166009. The reversal of 42165991 is 19956124.

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 42165991 - 2¹ = 42165989 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 42165991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42165191) 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, 3011850 + ... + 3011863.

It is an arithmetic number, because the mean of its divisors is an integer number (12047428).

Almost surely, 2^42165991 is an apocalyptic number.

42165991 is a deficient number, since it is larger than the sum of its proper divisors (6023721).

42165991 is an equidigital number, since it uses as much as digits as its factorization.

42165991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6023720.

The product of its digits is 19440, while the sum is 37.

The square root of 42165991 is about 6493.5345536926. The cubic root of 42165991 is about 348.0599904286.

The spelling of 42165991 in words is "forty-two million, one hundred sixty-five thousand, nine hundred ninety-one".