666501066561 has 32 divisors (see below), whose sum is σ = 980644496256. Its totient is φ = 399291200000.

The previous prime is 666501066527. The next prime is 666501066599. The reversal of 666501066561 is 165660105666.

It is not a de Polignac number, because 666501066561 - 2¹¹ = 666501064513 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 666501066561.

It is not an unprimeable number, because it can be changed into a prime (666501066521) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1894411 + ... + 2218511.

It is an arithmetic number, because the mean of its divisors is an integer number (30645140508).

Almost surely, 2^666501066561 is an apocalyptic number.

It is an amenable number.

666501066561 is a deficient number, since it is larger than the sum of its proper divisors (314143429695).

666501066561 is a wasteful number, since it uses less digits than its factorization.

666501066561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324833.

The product of its (nonzero) digits is 1166400, while the sum is 48.

The spelling of 666501066561 in words is "six hundred sixty-six billion, five hundred one million, sixty-six thousand, five hundred sixty-one".