666121350218605 has 8 divisors (see below), whose sum is σ = 799355507643000. Its totient is φ = 532890488587776.

The previous prime is 666121350218587. The next prime is 666121350218609. The reversal of 666121350218605 is 506812053121666.

It can be written as a sum of positive squares in 4 ways, for example, as 1081271384964 + 665040078833641 = 1039842^2 + 25788371^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 666121350218605 - 2¹¹ = 666121350216557 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666121350218609) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 823503720 + ... + 824312209.

It is an arithmetic number, because the mean of its divisors is an integer number (99919438455375).

Almost surely, 2^{666121350218605} is an apocalyptic number.

It is an amenable number.

666121350218605 is a deficient number, since it is larger than the sum of its proper divisors (133234157424395).

666121350218605 is a wasteful number, since it uses less digits than its factorization.

666121350218605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1647896783.

The product of its (nonzero) digits is 3110400, while the sum is 52.

The spelling of 666121350218605 in words is "six hundred sixty-six trillion, one hundred twenty-one billion, three hundred fifty million, two hundred eighteen thousand, six hundred five".