6645550081 has 2 divisors, whose sum is σ = 6645550082. Its totient is φ = 6645550080.

The previous prime is 6645550063. The next prime is 6645550099. The reversal of 6645550081 is 1800555466.

It is the 33281-st star number.

It is a balanced prime because it is at equal distance from previous prime (6645550063) and next prime (6645550099).

It can be written as a sum of positive squares in only one way, i.e., 3401222400 + 3244327681 = 58320^2 + 56959^2 .

It is a cyclic number.

It is not a de Polignac number, because 6645550081 - 2²⁷ = 6511332353 is a prime.

It is a super-3 number, since 3×6645550081³ (a number of 30 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (6645550031) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3322775040 + 3322775041.

It is an arithmetic number, because the mean of its divisors is an integer number (3322775041).

Almost surely, 2^6645550081 is an apocalyptic number.

It is an amenable number.

6645550081 is a deficient number, since it is larger than the sum of its proper divisors (1).

6645550081 is an equidigital number, since it uses as much as digits as its factorization.

6645550081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 144000, while the sum is 40.

The square root of 6645550081 is about 81520.2433816288. The cubic root of 6645550081 is about 1880.0828091825.

The spelling of 6645550081 in words is "six billion, six hundred forty-five million, five hundred fifty thousand, eighty-one".