42009181 has 2 divisors, whose sum is σ = 42009182. Its totient is φ = 42009180.

The previous prime is 42009179. The next prime is 42009203. The reversal of 42009181 is 18190024.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 26728900 + 15280281 = 5170^2 + 3909^2 .

It is a cyclic number.

It is not a de Polignac number, because 42009181 - 2¹ = 42009179 is a prime.

It is a super-2 number, since 2×42009181² = 3529542576581522, which contains 22 as substring.

Together with 42009179, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (42009101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 21004590 + 21004591.

It is an arithmetic number, because the mean of its divisors is an integer number (21004591).

Almost surely, 2^42009181 is an apocalyptic number.

It is an amenable number.

42009181 is a deficient number, since it is larger than the sum of its proper divisors (1).

42009181 is an equidigital number, since it uses as much as digits as its factorization.

42009181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 25.

The square root of 42009181 is about 6481.4489892307. The cubic root of 42009181 is about 347.6279907391.

The spelling of 42009181 in words is "forty-two million, nine thousand, one hundred eighty-one".