42856991 has 4 divisors (see below), whose sum is σ = 42900312. Its totient is φ = 42813672.

The previous prime is 42856987. The next prime is 42856993. The reversal of 42856991 is 19965824.

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 42856991 - 2² = 42856987 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 (42856993) 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, 20141 + ... + 22166.

It is an arithmetic number, because the mean of its divisors is an integer number (10725078).

Almost surely, 2^42856991 is an apocalyptic number.

42856991 is a deficient number, since it is larger than the sum of its proper divisors (43321).

42856991 is a wasteful number, since it uses less digits than its factorization.

42856991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43320.

The product of its digits is 155520, while the sum is 44.

The square root of 42856991 is about 6546.5251087886. The cubic root of 42856991 is about 349.9509890556.

The spelling of 42856991 in words is "forty-two million, eight hundred fifty-six thousand, nine hundred ninety-one".