66220261 has 2 divisors, whose sum is σ = 66220262. Its totient is φ = 66220260.

The previous prime is 66220229. The next prime is 66220279. The reversal of 66220261 is 16202266.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 53217025 + 13003236 = 7295^2 + 3606^2 .

It is a cyclic number.

It is not a de Polignac number, because 66220261 - 2⁵ = 66220229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66220211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33110130 + 33110131.

It is an arithmetic number, because the mean of its divisors is an integer number (33110131).

Almost surely, 2^66220261 is an apocalyptic number.

It is an amenable number.

66220261 is a deficient number, since it is larger than the sum of its proper divisors (1).

66220261 is an equidigital number, since it uses as much as digits as its factorization.

66220261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 66220261 is about 8137.5832407417. The cubic root of 66220261 is about 404.5730622622.

The spelling of 66220261 in words is "sixty-six million, two hundred twenty thousand, two hundred sixty-one".