6645505666 has 8 divisors (see below), whose sum is σ = 10554626700. Its totient is φ = 3127296768.

The previous prime is 6645505663. The next prime is 6645505687. The reversal of 6645505666 is 6665055466.

It can be written as a sum of positive squares in 2 ways, for example, as 6365646225 + 279859441 = 79785^2 + 16729^2 .

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

It is not an unprimeable number, because it can be changed into a prime (6645505663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 97727991 + ... + 97728058.

Almost surely, 2^6645505666 is an apocalyptic number.

6645505666 is a deficient number, since it is larger than the sum of its proper divisors (3909121034).

6645505666 is a wasteful number, since it uses less digits than its factorization.

6645505666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 195456068.

The product of its (nonzero) digits is 3888000, while the sum is 49.

The square root of 6645505666 is about 81519.9709641754. The cubic root of 6645505666 is about 1880.0786207124.

The spelling of 6645505666 in words is "six billion, six hundred forty-five million, five hundred five thousand, six hundred sixty-six".