665550559 has 2 divisors, whose sum is σ = 665550560. Its totient is φ = 665550558.

The previous prime is 665550553. The next prime is 665550577. The reversal of 665550559 is 955055566.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 665550559 - 2²³ = 657161951 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665550553) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332775279 + 332775280.

It is an arithmetic number, because the mean of its divisors is an integer number (332775280).

Almost surely, 2^665550559 is an apocalyptic number.

665550559 is a deficient number, since it is larger than the sum of its proper divisors (1).

665550559 is an equidigital number, since it uses as much as digits as its factorization.

665550559 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1012500, while the sum is 46.

The square root of 665550559 is about 25798.2665890559. The cubic root of 665550559 is about 873.0926875019.

The spelling of 665550559 in words is "six hundred sixty-five million, five hundred fifty thousand, five hundred fifty-nine".