1666685018520 has 64 divisors (see below), whose sum is σ = 5555616732000. Its totient is φ = 444449337984.

The previous prime is 1666685018513. The next prime is 1666685018617. The reversal of 1666685018520 is 258105866661.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 771612355 + ... + 771614514.

Almost surely, 2^{1666685018520} is an apocalyptic number.

1666685018520 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1666685018520 is an abundant number, since it is smaller than the sum of its proper divisors (3888931713480).

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

1666685018520 is a wasteful number, since it uses less digits than its factorization.

1666685018520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1543226889 (or 1543226879 counting only the distinct ones).

The product of its (nonzero) digits is 4147200, while the sum is 54.

The spelling of 1666685018520 in words is "one trillion, six hundred sixty-six billion, six hundred eighty-five million, eighteen thousand, five hundred twenty".