63981 has 6 divisors (see below), whose sum is σ = 92430. Its totient is φ = 42648.

The previous prime is 63977. The next prime is 63997. The reversal of 63981 is 18936.

It can be written as a sum of positive squares in only one way, i.e., 44100 + 19881 = 210^2 + 141^2 .

It is not a de Polignac number, because 63981 - 2² = 63977 is a prime.

It is a super-2 number, since 2×63981² = 8187136722, which contains 22 as substring.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 63981.

It is not an unprimeable number, because it can be changed into a prime (63901) 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, 3546 + ... + 3563.

It is an arithmetic number, because the mean of its divisors is an integer number (15405).

2⁶³⁹⁸¹ is an apocalyptic number.

It is an amenable number.

63981 is a deficient number, since it is larger than the sum of its proper divisors (28449).

63981 is a wasteful number, since it uses less digits than its factorization.

63981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7115 (or 7112 counting only the distinct ones).

The product of its digits is 1296, while the sum is 27.

The square root of 63981 is about 252.9446579788. The cubic root of 63981 is about 39.9960412749.

The spelling of 63981 in words is "sixty-three thousand, nine hundred eighty-one".