66820289 has 2 divisors, whose sum is σ = 66820290. Its totient is φ = 66820288.

The previous prime is 66820279. The next prime is 66820291. The reversal of 66820289 is 98202866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 52128400 + 14691889 = 7220^2 + 3833^2 .

It is a cyclic number.

It is not a de Polignac number, because 66820289 - 2²⁴ = 50043073 is a prime.

Together with 66820291, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (66820249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33410144 + 33410145.

It is an arithmetic number, because the mean of its divisors is an integer number (33410145).

Almost surely, 2^66820289 is an apocalyptic number.

It is an amenable number.

66820289 is a deficient number, since it is larger than the sum of its proper divisors (1).

66820289 is an equidigital number, since it uses as much as digits as its factorization.

66820289 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 82944, while the sum is 41.

The square root of 66820289 is about 8174.3678043014. The cubic root of 66820289 is about 405.7913481333.

The spelling of 66820289 in words is "sixty-six million, eight hundred twenty thousand, two hundred eighty-nine".