66639 has 8 divisors (see below), whose sum is σ = 90160. Its totient is φ = 43776.

The previous prime is 66629. The next prime is 66643. The reversal of 66639 is 93666.

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

It is not a de Polignac number, because 66639 - 2⁸ = 66383 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66629) 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, 177 + ... + 405.

It is an arithmetic number, because the mean of its divisors is an integer number (11270).

2⁶⁶⁶³⁹ is an apocalyptic number.

66639 is a deficient number, since it is larger than the sum of its proper divisors (23521).

66639 is a wasteful number, since it uses less digits than its factorization.

66639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329.

The product of its digits is 5832, while the sum is 30.

The square root of 66639 is about 258.1453079178. The cubic root of 66639 is about 40.5424033859.

The spelling of 66639 in words is "sixty-six thousand, six hundred thirty-nine".