201681 has 6 divisors (see below), whose sum is σ = 291330. Its totient is φ = 134448.

The previous prime is 201673. The next prime is 201683. The reversal of 201681 is 186102.

201681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 176400 + 25281 = 420^2 + 159^2 .

It is not a de Polignac number, because 201681 - 2³ = 201673 is a prime.

It is a super-2 number, since 2×201681² = 81350451522, which contains 22 as substring.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 201681.

It is not an unprimeable number, because it can be changed into a prime (201683) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11196 + ... + 11213.

It is an arithmetic number, because the mean of its divisors is an integer number (48555).

2²⁰¹⁶⁸¹ is an apocalyptic number.

It is an amenable number.

201681 is a deficient number, since it is larger than the sum of its proper divisors (89649).

201681 is a wasteful number, since it uses less digits than its factorization.

201681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22415 (or 22412 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 201681 is about 449.0890780235. The cubic root of 201681 is about 58.6437403244.

Adding to 201681 its reverse (186102), we get a palindrome (387783).

The spelling of 201681 in words is "two hundred one thousand, six hundred eighty-one".