66665 has 8 divisors (see below), whose sum is σ = 81600. Its totient is φ = 52272.

The previous prime is 66653. The next prime is 66683. The reversal of 66665 is 56666.

66665 is an esthetic number in base 6, because in such base its adjacent digits differ by 1.

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 66665 - 2⁶ = 66601 is a prime.

It is a super-4 number, since 4×66665⁴ = 79004444740735802500, which contains 4444 as substring.

It is a nialpdrome in base 10.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 236 + ... + 434.

It is an arithmetic number, because the mean of its divisors is an integer number (10200).

2⁶⁶⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

66665 is a deficient number, since it is larger than the sum of its proper divisors (14935).

66665 is a wasteful number, since it uses less digits than its factorization.

66665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 271.

The product of its digits is 6480, while the sum is 29.

The square root of 66665 is about 258.1956622409. The cubic root of 66665 is about 40.5476754009.

Subtracting from 66665 its reverse (56666), we obtain a palindrome (9999).

The spelling of 66665 in words is "sixty-six thousand, six hundred sixty-five".