666455509 has 2 divisors, whose sum is σ = 666455510. Its totient is φ = 666455508.

The previous prime is 666455497. The next prime is 666455519. The reversal of 666455509 is 905554666.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 662032900 + 4422609 = 25730^2 + 2103^2 .

It is a cyclic number.

It is not a de Polignac number, because 666455509 - 2¹³ = 666447317 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666455519) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333227754 + 333227755.

It is an arithmetic number, because the mean of its divisors is an integer number (333227755).

Almost surely, 2^666455509 is an apocalyptic number.

It is an amenable number.

666455509 is a deficient number, since it is larger than the sum of its proper divisors (1).

666455509 is an equidigital number, since it uses as much as digits as its factorization.

666455509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 972000, while the sum is 46.

The square root of 666455509 is about 25815.7996002448. The cubic root of 666455509 is about 873.4882233906.

The spelling of 666455509 in words is "six hundred sixty-six million, four hundred fifty-five thousand, five hundred nine".