665660478949 has 2 divisors, whose sum is σ = 665660478950. Its totient is φ = 665660478948.

The previous prime is 665660478803. The next prime is 665660479069. The reversal of 665660478949 is 949874066566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 411259277025 + 254401201924 = 641295^2 + 504382^2 .

It is a cyclic number.

It is not a de Polignac number, because 665660478949 - 2¹³ = 665660470757 is a prime.

It is a super-2 number, since 2×665660478949² (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 (665660458949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332830239474 + 332830239475.

It is an arithmetic number, because the mean of its divisors is an integer number (332830239475).

Almost surely, 2^665660478949 is an apocalyptic number.

It is an amenable number.

665660478949 is a deficient number, since it is larger than the sum of its proper divisors (1).

665660478949 is an equidigital number, since it uses as much as digits as its factorization.

665660478949 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 470292480, while the sum is 70.

The spelling of 665660478949 in words is "six hundred sixty-five billion, six hundred sixty million, four hundred seventy-eight thousand, nine hundred forty-nine".