840181 has 2 divisors, whose sum is σ = 840182. Its totient is φ = 840180.

The previous prime is 840179. The next prime is 840187. The reversal of 840181 is 181048.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 555025 + 285156 = 745^2 + 534^2 .

It is a cyclic number.

It is not a de Polignac number, because 840181 - 2¹ = 840179 is a prime.

It is a super-2 number, since 2×840181² = 1411808225522, which contains 22 as substring.

Together with 840179, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (840187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 420090 + 420091.

It is an arithmetic number, because the mean of its divisors is an integer number (420091).

2⁸⁴⁰¹⁸¹ is an apocalyptic number.

It is an amenable number.

840181 is a deficient number, since it is larger than the sum of its proper divisors (1).

840181 is an equidigital number, since it uses as much as digits as its factorization.

840181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 256, while the sum is 22.

The square root of 840181 is about 916.6138772678. The cubic root of 840181 is about 94.3606561245.

The spelling of 840181 in words is "eight hundred forty thousand, one hundred eighty-one".