666820504686 has 32 divisors (see below), whose sum is σ = 1524358487808. Its totient is φ = 190495477440.

The previous prime is 666820504633. The next prime is 666820504687. The reversal of 666820504686 is 686405028666.

666820504686 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Smith number, since the sum of its digits (57) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666820504687) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 698280 + ... + 1349531.

It is an arithmetic number, because the mean of its divisors is an integer number (47636202744).

Almost surely, 2^666820504686 is an apocalyptic number.

666820504686 is an abundant number, since it is smaller than the sum of its proper divisors (857537983122).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

666820504686 is a wasteful number, since it uses less digits than its factorization.

666820504686 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2055576.

The product of its (nonzero) digits is 19906560, while the sum is 57.

The spelling of 666820504686 in words is "six hundred sixty-six billion, eight hundred twenty million, five hundred four thousand, six hundred eighty-six".