665585078399 has 4 divisors (see below), whose sum is σ = 666857708136. Its totient is φ = 664312448664.

The previous prime is 665585078339. The next prime is 665585078471. The reversal of 665585078399 is 993870585566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 993870585566 = 2 ⋅496935292783.

It is a cyclic number.

It is not a de Polignac number, because 665585078399 - 2⁸ = 665585078143 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665585078309) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 636314084 + ... + 636315129.

It is an arithmetic number, because the mean of its divisors is an integer number (166714427034).

Almost surely, 2^665585078399 is an apocalyptic number.

665585078399 is a deficient number, since it is larger than the sum of its proper divisors (1272629737).

665585078399 is a wasteful number, since it uses less digits than its factorization.

665585078399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1272629736.

The product of its (nonzero) digits is 489888000, while the sum is 71.

The spelling of 665585078399 in words is "six hundred sixty-five billion, five hundred eighty-five million, seventy-eight thousand, three hundred ninety-nine".