66409 has 8 divisors (see below), whose sum is σ = 77760. Its totient is φ = 55536.

The previous prime is 66403. The next prime is 66413. The reversal of 66409 is 90466.

66409 is nontrivially palindromic in base 5.

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 66409 - 2⁵ = 66377 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 (66403) 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, 282 + ... + 460.

It is an arithmetic number, because the mean of its divisors is an integer number (9720).

2⁶⁶⁴⁰⁹ is an apocalyptic number.

It is an amenable number.

66409 is a deficient number, since it is larger than the sum of its proper divisors (11351).

66409 is a wasteful number, since it uses less digits than its factorization.

66409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 239.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 66409 is about 257.6994373296. The cubic root of 66409 is about 40.4957065001.

The spelling of 66409 in words is "sixty-six thousand, four hundred nine".