66891 has 8 divisors (see below), whose sum is σ = 97344. Its totient is φ = 40520.

The previous prime is 66889. The next prime is 66919. The reversal of 66891 is 19866.

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 66891 - 2¹ = 66889 is a prime.

66891 is a modest number, since divided by 891 gives 66 as remainder.

It is not an unprimeable number, because it can be changed into a prime (66821) 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, 981 + ... + 1046.

It is an arithmetic number, because the mean of its divisors is an integer number (12168).

2⁶⁶⁸⁹¹ is an apocalyptic number.

66891 is a deficient number, since it is larger than the sum of its proper divisors (30453).

66891 is a wasteful number, since it uses less digits than its factorization.

66891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2041.

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

The square root of 66891 is about 258.6329445372. The cubic root of 66891 is about 40.5934437390.

The spelling of 66891 in words is "sixty-six thousand, eight hundred ninety-one".