1666728503646 has 8 divisors (see below), whose sum is σ = 3333457007304. Its totient is φ = 555576167880.

The previous prime is 1666728503639. The next prime is 1666728503689. The reversal of 1666728503646 is 6463058276661.

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

1666728503646 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 1666728503646.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 138894041965 + ... + 138894041976.

It is an arithmetic number, because the mean of its divisors is an integer number (416682125913).

Almost surely, 2^{1666728503646} is an apocalyptic number.

1666728503646 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

1666728503646 is a wasteful number, since it uses less digits than its factorization.

1666728503646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277788083946.

The product of its (nonzero) digits is 52254720, while the sum is 60.

The spelling of 1666728503646 in words is "one trillion, six hundred sixty-six billion, seven hundred twenty-eight million, five hundred three thousand, six hundred forty-six".