66216109 has 2 divisors, whose sum is σ = 66216110. Its totient is φ = 66216108.

The previous prime is 66216097. The next prime is 66216151. The reversal of 66216109 is 90161266.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 60016009 + 6200100 = 7747^2 + 2490^2 .

It is a cyclic number.

It is not a de Polignac number, because 66216109 - 2²³ = 57827501 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66216209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33108054 + 33108055.

It is an arithmetic number, because the mean of its divisors is an integer number (33108055).

Almost surely, 2^66216109 is an apocalyptic number.

It is an amenable number.

66216109 is a deficient number, since it is larger than the sum of its proper divisors (1).

66216109 is an equidigital number, since it uses as much as digits as its factorization.

66216109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 66216109 is about 8137.3281241449. The cubic root of 66216109 is about 404.5646065296.

The spelling of 66216109 in words is "sixty-six million, two hundred sixteen thousand, one hundred nine".