6661858566 has 32 divisors (see below), whose sum is σ = 14544914688. Its totient is φ = 2017363040.

The previous prime is 6661858523. The next prime is 6661858571. The reversal of 6661858566 is 6658581666.

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, 64735 + ... + 132341.

It is an arithmetic number, because the mean of its divisors is an integer number (454528584).

Almost surely, 2^6661858566 is an apocalyptic number.

6661858566 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

6661858566 is an abundant number, since it is smaller than the sum of its proper divisors (7883056122).

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

6661858566 is a wasteful number, since it uses less digits than its factorization.

6661858566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69116.

The product of its digits is 12441600, while the sum is 57.

The square root of 6661858566 is about 81620.2092989230. The cubic root of 6661858566 is about 1881.6194893491.

The spelling of 6661858566 in words is "six billion, six hundred sixty-one million, eight hundred fifty-eight thousand, five hundred sixty-six".