666344989477 has 2 divisors, whose sum is σ = 666344989478. Its totient is φ = 666344989476.

The previous prime is 666344989447. The next prime is 666344989481. The reversal of 666344989477 is 774989443666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 578016555076 + 88328434401 = 760274^2 + 297201^2 .

It is a cyclic number.

It is not a de Polignac number, because 666344989477 - 2²⁷ = 666210771749 is a prime.

It is a super-2 number, since 2×666344989477² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666344989447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333172494738 + 333172494739.

It is an arithmetic number, because the mean of its divisors is an integer number (333172494739).

Almost surely, 2^666344989477 is an apocalyptic number.

It is an amenable number.

666344989477 is a deficient number, since it is larger than the sum of its proper divisors (1).

666344989477 is an equidigital number, since it uses as much as digits as its factorization.

666344989477 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1316818944, while the sum is 73.

The spelling of 666344989477 in words is "six hundred sixty-six billion, three hundred forty-four million, nine hundred eighty-nine thousand, four hundred seventy-seven".