6655555561 has 2 divisors, whose sum is σ = 6655555562. Its totient is φ = 6655555560.

The previous prime is 6655555541. The next prime is 6655555567. The reversal of 6655555561 is 1655555566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6635079936 + 20475625 = 81456^2 + 4525^2 .

It is a cyclic number.

It is not a de Polignac number, because 6655555561 - 2¹⁵ = 6655522793 is a prime.

It is not a weakly prime, because it can be changed into another prime (6655555567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3327777780 + 3327777781.

It is an arithmetic number, because the mean of its divisors is an integer number (3327777781).

Almost surely, 2^6655555561 is an apocalyptic number.

It is an amenable number.

6655555561 is a deficient number, since it is larger than the sum of its proper divisors (1).

6655555561 is an equidigital number, since it uses as much as digits as its factorization.

6655555561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3375000, while the sum is 49.

The square root of 6655555561 is about 81581.5883701709. The cubic root of 6655555561 is about 1881.0258812624.

The spelling of 6655555561 in words is "six billion, six hundred fifty-five million, five hundred fifty-five thousand, five hundred sixty-one".