66211811 has 4 divisors (see below), whose sum is σ = 66345000. Its totient is φ = 66078624.

The previous prime is 66211807. The next prime is 66211823. The reversal of 66211811 is 11811266.

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

It is a cyclic number.

It is not a de Polignac number, because 66211811 - 2² = 66211807 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66211801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65846 + ... + 66843.

It is an arithmetic number, because the mean of its divisors is an integer number (16586250).

Almost surely, 2^66211811 is an apocalyptic number.

66211811 is a deficient number, since it is larger than the sum of its proper divisors (133189).

66211811 is a wasteful number, since it uses less digits than its factorization.

66211811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133188.

The product of its digits is 576, while the sum is 26.

The square root of 66211811 is about 8137.0640282598. The cubic root of 66211811 is about 404.5558530892. Note that the first 3 decimals are identical.

The spelling of 66211811 in words is "sixty-six million, two hundred eleven thousand, eight hundred eleven".