66378501509 has 2 divisors, whose sum is σ = 66378501510. Its totient is φ = 66378501508.

The previous prime is 66378501503. The next prime is 66378501557. The reversal of 66378501509 is 90510587366.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 46995736225 + 19382765284 = 216785^2 + 139222^2 .

It is a cyclic number.

It is not a de Polignac number, because 66378501509 - 2¹⁶ = 66378435973 is a prime.

It is a super-2 number, since 2×66378501509² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66378501503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33189250754 + 33189250755.

It is an arithmetic number, because the mean of its divisors is an integer number (33189250755).

Almost surely, 2^66378501509 is an apocalyptic number.

It is an amenable number.

66378501509 is a deficient number, since it is larger than the sum of its proper divisors (1).

66378501509 is an equidigital number, since it uses as much as digits as its factorization.

66378501509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1360800, while the sum is 50.

The spelling of 66378501509 in words is "sixty-six billion, three hundred seventy-eight million, five hundred one thousand, five hundred nine".