66709 has 4 divisors (see below), whose sum is σ = 70240. Its totient is φ = 63180.

The previous prime is 66701. The next prime is 66713. The reversal of 66709 is 90766.

66709 = T₁₇ + T₁₈ + ... + T₇₃.

66709 = 50² + 51² + ... + 68².

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 66709 - 2³ = 66701 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 (66701) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1737 + ... + 1774.

It is an arithmetic number, because the mean of its divisors is an integer number (17560).

2⁶⁶⁷⁰⁹ is an apocalyptic number.

It is an amenable number.

66709 is a deficient number, since it is larger than the sum of its proper divisors (3531).

66709 is a wasteful number, since it uses less digits than its factorization.

66709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3530.

The product of its (nonzero) digits is 2268, while the sum is 28.

The square root of 66709 is about 258.2808548848. The cubic root of 66709 is about 40.5565941506.

The spelling of 66709 in words is "sixty-six thousand, seven hundred nine".