665447216666 has 16 divisors (see below), whose sum is σ = 999577768680. Its totient is φ = 332254771200.

The previous prime is 665447216587. The next prime is 665447216671. The reversal of 665447216666 is 666612744566.

It can be written as a sum of positive squares in 4 ways, for example, as 663499848025 + 1947368641 = 814555^2 + 44129^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10220816 + ... + 10285716.

Almost surely, 2^665447216666 is an apocalyptic number.

665447216666 is a deficient number, since it is larger than the sum of its proper divisors (334130552014).

665447216666 is a wasteful number, since it uses less digits than its factorization.

665447216666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72049.

The product of its digits is 52254720, while the sum is 59.

The spelling of 665447216666 in words is "six hundred sixty-five billion, four hundred forty-seven million, two hundred sixteen thousand, six hundred sixty-six".