6657805661 has 4 divisors (see below), whose sum is σ = 7169944572. Its totient is φ = 6145666752.

The previous prime is 6657805631. The next prime is 6657805663. The reversal of 6657805661 is 1665087566.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2734662436 + 3923143225 = 52294^2 + 62635^2 .

It is a cyclic number.

It is not a de Polignac number, because 6657805661 - 2¹⁸ = 6657543517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6657805663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 256069436 + ... + 256069461.

It is an arithmetic number, because the mean of its divisors is an integer number (1792486143).

Almost surely, 2^6657805661 is an apocalyptic number.

It is an amenable number.

6657805661 is a deficient number, since it is larger than the sum of its proper divisors (512138911).

6657805661 is a wasteful number, since it uses less digits than its factorization.

6657805661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 512138910.

The product of its (nonzero) digits is 1814400, while the sum is 50.

The square root of 6657805661 is about 81595.3776938375. The cubic root of 6657805661 is about 1881.2378354920.

The spelling of 6657805661 in words is "six billion, six hundred fifty-seven million, eight hundred five thousand, six hundred sixty-one".