666556601505 has 64 divisors (see below), whose sum is σ = 1159744634880. Its totient is φ = 325666656000.

The previous prime is 666556601489. The next prime is 666556601509. The reversal of 666556601505 is 505106655666.

666556601505 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 666556601505 - 2⁴ = 666556601489 is a prime.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (666556601509) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 11483055 + ... + 11540955.

It is an arithmetic number, because the mean of its divisors is an integer number (18121009920).

Almost surely, 2^666556601505 is an apocalyptic number.

It is an amenable number.

666556601505 is a deficient number, since it is larger than the sum of its proper divisors (493188033375).

666556601505 is a wasteful number, since it uses less digits than its factorization.

666556601505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59262.

The product of its (nonzero) digits is 4860000, while the sum is 51.

The spelling of 666556601505 in words is "six hundred sixty-six billion, five hundred fifty-six million, six hundred one thousand, five hundred five".