42391 has 2 divisors, whose sum is σ = 42392. Its totient is φ = 42390.

The previous prime is 42379. The next prime is 42397. The reversal of 42391 is 19324.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 42391 - 2⁵ = 42359 is a prime.

42391 is a lucky number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21195 + 21196.

It is an arithmetic number, because the mean of its divisors is an integer number (21196).

2⁴²³⁹¹ is an apocalyptic number.

42391 is a deficient number, since it is larger than the sum of its proper divisors (1).

42391 is an equidigital number, since it uses as much as digits as its factorization.

42391 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 216, while the sum is 19.

The square root of 42391 is about 205.8907477280. The cubic root of 42391 is about 34.8678006148.

The spelling of 42391 in words is "forty-two thousand, three hundred ninety-one".