210681 has 21 divisors (see below), whose sum is σ = 335551. Its totient is φ = 132192.

The previous prime is 210671. The next prime is 210709. The reversal of 210681 is 186012.

210681 = T₄₅₈ + T₄₅₉.

The square root of 210681 is 459.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 164025 + 46656 = 405^2 + 216^2 .

It is not a de Polignac number, because 210681 - 2⁹ = 210169 is a prime.

It is a super-2 number, since 2×210681² = 88772967522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (210601) by changing a digit.

It is a polite number, since it can be written in 20 ways as a sum of consecutive naturals, for example, 12385 + ... + 12401.

210681 is a Friedman number, since it can be written as 2601*81, using all its digits and the basic arithmetic operations.

2²¹⁰⁶⁸¹ is an apocalyptic number.

210681 is the 459-th square number.

210681 is the 230-th centered octagonal number.

It is an amenable number.

210681 is a deficient number, since it is larger than the sum of its proper divisors (124870).

210681 is an frugal number, since it uses more digits than its factorization.

210681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52 (or 20 counting only the distinct ones).

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

The cubic root of 210681 is about 59.5034011661.

Adding to 210681 its reverse (186012), we get a palindrome (396693).

It can be divided in two parts, 2106 and 81, that added together give a 7-th power (2187 = 3⁷).

The spelling of 210681 in words is "two hundred ten thousand, six hundred eighty-one".