65811 has 4 divisors (see below), whose sum is σ = 87752. Its totient is φ = 43872.

The previous prime is 65809. The next prime is 65827. The reversal of 65811 is 11856.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 65811 - 2¹ = 65809 is a prime.

It is a D-number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (65831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10966 + ... + 10971.

It is an arithmetic number, because the mean of its divisors is an integer number (21938).

2⁶⁵⁸¹¹ is an apocalyptic number.

65811 is a deficient number, since it is larger than the sum of its proper divisors (21941).

65811 is a wasteful number, since it uses less digits than its factorization.

65811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21940.

The product of its digits is 240, while the sum is 21.

The square root of 65811 is about 256.5365471039. The cubic root of 65811 is about 40.3737878526.

The spelling of 65811 in words is "sixty-five thousand, eight hundred eleven".