63681 has 4 divisors (see below), whose sum is σ = 84912. Its totient is φ = 42452.

The previous prime is 63671. The next prime is 63689. The reversal of 63681 is 18636.

63681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 63681 - 2⁵ = 63649 is a prime.

It is a super-2 number, since 2×63681² = 8110539522, which contains 22 as substring.

It is a D-number.

It is a Curzon number.

63681 is a lucky number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 63681.

It is not an unprimeable number, because it can be changed into a prime (63689) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10611 + ... + 10616.

It is an arithmetic number, because the mean of its divisors is an integer number (21228).

2⁶³⁶⁸¹ is an apocalyptic number.

It is an amenable number.

63681 is a deficient number, since it is larger than the sum of its proper divisors (21231).

63681 is a wasteful number, since it uses less digits than its factorization.

63681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21230.

The product of its digits is 864, while the sum is 24.

The square root of 63681 is about 252.3509461048. The cubic root of 63681 is about 39.9334309421.

It can be divided in two parts, 636 and 81, that added together give a palindrome (717).

The spelling of 63681 in words is "sixty-three thousand, six hundred eighty-one".