66216971 has 4 divisors (see below), whose sum is σ = 67205352. Its totient is φ = 65228592.

The previous prime is 66216929. The next prime is 66217027. The reversal of 66216971 is 17961266.

66216971 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 66216971 - 2¹⁴ = 66200587 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66216901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 494090 + ... + 494223.

It is an arithmetic number, because the mean of its divisors is an integer number (16801338).

Almost surely, 2^66216971 is an apocalyptic number.

66216971 is a deficient number, since it is larger than the sum of its proper divisors (988381).

66216971 is an equidigital number, since it uses as much as digits as its factorization.

66216971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 988380.

The product of its digits is 27216, while the sum is 38.

The square root of 66216971 is about 8137.3810897610. The cubic root of 66216971 is about 404.5663620600.

The spelling of 66216971 in words is "sixty-six million, two hundred sixteen thousand, nine hundred seventy-one".