42091991 has 8 divisors (see below), whose sum is σ = 42614784. Its totient is φ = 41572440.

The previous prime is 42091967. The next prime is 42091993. The reversal of 42091991 is 19919024.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 42091991 - 2²² = 37897687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (42091993) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33806 + ... + 35028.

It is an arithmetic number, because the mean of its divisors is an integer number (5326848).

Almost surely, 2^42091991 is an apocalyptic number.

42091991 is a deficient number, since it is larger than the sum of its proper divisors (522793).

42091991 is a wasteful number, since it uses less digits than its factorization.

42091991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1621.

The product of its (nonzero) digits is 5832, while the sum is 35.

The square root of 42091991 is about 6487.8340761767. The cubic root of 42091991 is about 347.8562597233.

The spelling of 42091991 in words is "forty-two million, ninety-one thousand, nine hundred ninety-one".