66511 has 4 divisors (see below), whose sum is σ = 67032. Its totient is φ = 65992.

The previous prime is 66509. The next prime is 66523. The reversal of 66511 is 11566.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 11566 = 2 ⋅5783.

It is a cyclic number.

It is not a de Polignac number, because 66511 - 2¹ = 66509 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66541) 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, 81 + ... + 373.

It is an arithmetic number, because the mean of its divisors is an integer number (16758).

2⁶⁶⁵¹¹ is an apocalyptic number.

66511 is a deficient number, since it is larger than the sum of its proper divisors (521).

66511 is a wasteful number, since it uses less digits than its factorization.

66511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 520.

The product of its digits is 180, while the sum is 19.

The square root of 66511 is about 257.8972663678. The cubic root of 66511 is about 40.5164288375.

Subtracting from 66511 its reverse (11566), we obtain a palindrome (54945).

It can be divided in two parts, 665 and 11, that added together give a palindrome (676).

The spelling of 66511 in words is "sixty-six thousand, five hundred eleven".