66662509 has 2 divisors, whose sum is σ = 66662510. Its totient is φ = 66662508.

The previous prime is 66662489. The next prime is 66662549. The reversal of 66662509 is 90526666.

It is an a-pointer prime, because the next prime (66662549) can be obtained adding 66662509 to its sum of digits (40).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 39100009 + 27562500 = 6253^2 + 5250^2 .

It is a cyclic number.

It is not a de Polignac number, because 66662509 - 2¹³ = 66654317 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66662549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33331254 + 33331255.

It is an arithmetic number, because the mean of its divisors is an integer number (33331255).

Almost surely, 2^66662509 is an apocalyptic number.

It is an amenable number.

66662509 is a deficient number, since it is larger than the sum of its proper divisors (1).

66662509 is an equidigital number, since it uses as much as digits as its factorization.

66662509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 116640, while the sum is 40.

The square root of 66662509 is about 8164.7112012612. The cubic root of 66662509 is about 405.4717036068.

The spelling of 66662509 in words is "sixty-six million, six hundred sixty-two thousand, five hundred nine".