42181891 has 2 divisors, whose sum is σ = 42181892. Its totient is φ = 42181890.

The previous prime is 42181871. The next prime is 42181897. The reversal of 42181891 is 19818124.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 42181891 - 2⁵ = 42181859 is a prime.

It is not a weakly prime, because it can be changed into another prime (42181897) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21090945 + 21090946.

It is an arithmetic number, because the mean of its divisors is an integer number (21090946).

Almost surely, 2^42181891 is an apocalyptic number.

42181891 is a deficient number, since it is larger than the sum of its proper divisors (1).

42181891 is an equidigital number, since it uses as much as digits as its factorization.

42181891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4608, while the sum is 34.

The square root of 42181891 is about 6494.7587330093. The cubic root of 42181891 is about 348.1037338835.

The spelling of 42181891 in words is "forty-two million, one hundred eighty-one thousand, eight hundred ninety-one".