66905 has 4 divisors (see below), whose sum is σ = 80292. Its totient is φ = 53520.

The previous prime is 66889. The next prime is 66919. The reversal of 66905 is 50966.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15376 + 51529 = 124^2 + 227^2 .

It is not a de Polignac number, because 66905 - 2⁴ = 66889 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 9.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 6686 + ... + 6695.

It is an arithmetic number, because the mean of its divisors is an integer number (20073).

2⁶⁶⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

66905 is a deficient number, since it is larger than the sum of its proper divisors (13387).

66905 is a wasteful number, since it uses less digits than its factorization.

66905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13386.

The product of its (nonzero) digits is 1620, while the sum is 26.

The square root of 66905 is about 258.6600085054. The cubic root of 66905 is about 40.5962755528.

The spelling of 66905 in words is "sixty-six thousand, nine hundred five".