66981 has 8 divisors (see below), whose sum is σ = 90720. Its totient is φ = 43952.

The previous prime is 66977. The next prime is 67003. The reversal of 66981 is 18966.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66981 - 2² = 66977 is a prime.

It is a super-2 number, since 2×66981² = 8972908722, which contains 22 as substring.

It is a Curzon number.

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 66981.

It is not an unprimeable number, because it can be changed into a prime (66931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 115 + ... + 383.

It is an arithmetic number, because the mean of its divisors is an integer number (11340).

2⁶⁶⁹⁸¹ is an apocalyptic number.

It is an amenable number.

66981 is a deficient number, since it is larger than the sum of its proper divisors (23739).

66981 is a wasteful number, since it uses less digits than its factorization.

66981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355.

The product of its digits is 2592, while the sum is 30.

The square root of 66981 is about 258.8068778066. The cubic root of 66981 is about 40.6116413672.

It can be divided in two parts, 66 and 981, that multiplied together give a palindrome (64746).

The spelling of 66981 in words is "sixty-six thousand, nine hundred eighty-one".