6651661566 has 16 divisors (see below), whose sum is σ = 14512716288. Its totient is φ = 2015655000.

The previous prime is 6651661561. The next prime is 6651661567.

6651661566 is nontrivially palindromic in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6651661561) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 50391310 + ... + 50391441.

It is an arithmetic number, because the mean of its divisors is an integer number (907044768).

Almost surely, 2^6651661566 is an apocalyptic number.

6651661566 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

6651661566 is an abundant number, since it is smaller than the sum of its proper divisors (7861054722).

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

6651661566 is a wasteful number, since it uses less digits than its factorization.

6651661566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 100782767.

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

The square root of 6651661566 is about 81557.7192300030. The cubic root of 6651661566 is about 1880.6589630153.

The spelling of 6651661566 in words is "six billion, six hundred fifty-one million, six hundred sixty-one thousand, five hundred sixty-six".