665447216573 has 4 divisors (see below), whose sum is σ = 671336130108. Its totient is φ = 659558303040.

The previous prime is 665447216569. The next prime is 665447216587. The reversal of 665447216573 is 375612744566.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 33554179684 + 631893036889 = 183178^2 + 794917^2 .

It is a cyclic number.

It is not a de Polignac number, because 665447216573 - 2² = 665447216569 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 (665447116573) 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, 2944456598 + ... + 2944456823.

It is an arithmetic number, because the mean of its divisors is an integer number (167834032527).

Almost surely, 2^665447216573 is an apocalyptic number.

It is an amenable number.

665447216573 is a deficient number, since it is larger than the sum of its proper divisors (5888913535).

665447216573 is a wasteful number, since it uses less digits than its factorization.

665447216573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5888913534.

The product of its digits is 25401600, while the sum is 56.

The spelling of 665447216573 in words is "six hundred sixty-five billion, four hundred forty-seven million, two hundred sixteen thousand, five hundred seventy-three".