66612109 has 2 divisors, whose sum is σ = 66612110. Its totient is φ = 66612108.

The previous prime is 66612083. The next prime is 66612127. The reversal of 66612109 is 90121666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 55086084 + 11526025 = 7422^2 + 3395^2 .

It is a cyclic number.

It is not a de Polignac number, because 66612109 - 2¹³ = 66603917 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66618109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33306054 + 33306055.

It is an arithmetic number, because the mean of its divisors is an integer number (33306055).

Almost surely, 2^66612109 is an apocalyptic number.

It is an amenable number.

66612109 is a deficient number, since it is larger than the sum of its proper divisors (1).

66612109 is an equidigital number, since it uses as much as digits as its factorization.

66612109 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 66612109 is about 8161.6241643438. The cubic root of 66612109 is about 405.3694926016.

The spelling of 66612109 in words is "sixty-six million, six hundred twelve thousand, one hundred nine".