66261604289 has 2 divisors, whose sum is σ = 66261604290. Its totient is φ = 66261604288.

The previous prime is 66261604267. The next prime is 66261604307. The reversal of 66261604289 is 98240616266.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 54599332225 + 11662272064 = 233665^2 + 107992^2 .

It is a cyclic number.

It is not a de Polignac number, because 66261604289 - 2¹⁶ = 66261538753 is a prime.

It is not a weakly prime, because it can be changed into another prime (66261604219) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33130802144 + 33130802145.

It is an arithmetic number, because the mean of its divisors is an integer number (33130802145).

Almost surely, 2^66261604289 is an apocalyptic number.

It is an amenable number.

66261604289 is a deficient number, since it is larger than the sum of its proper divisors (1).

66261604289 is an equidigital number, since it uses as much as digits as its factorization.

66261604289 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1492992, while the sum is 50.

The spelling of 66261604289 in words is "sixty-six billion, two hundred sixty-one million, six hundred four thousand, two hundred eighty-nine".