666620771 has 2 divisors, whose sum is σ = 666620772. Its totient is φ = 666620770.

The previous prime is 666620737. The next prime is 666620789. The reversal of 666620771 is 177026666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 666620771 - 2²² = 662426467 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (666620791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333310385 + 333310386.

It is an arithmetic number, because the mean of its divisors is an integer number (333310386).

Almost surely, 2^666620771 is an apocalyptic number.

666620771 is a deficient number, since it is larger than the sum of its proper divisors (1).

666620771 is an equidigital number, since it uses as much as digits as its factorization.

666620771 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 127008, while the sum is 41.

The square root of 666620771 is about 25819.0001936558. Note that the first 3 decimals coincide. The cubic root of 666620771 is about 873.5604174973.

The spelling of 666620771 in words is "six hundred sixty-six million, six hundred twenty thousand, seven hundred seventy-one".