6605500021 has 2 divisors, whose sum is σ = 6605500022. Its totient is φ = 6605500020.

The previous prime is 6605500003. The next prime is 6605500061. The reversal of 6605500021 is 1200055066.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 5884577521 + 720922500 = 76711^2 + 26850^2 .

It is a cyclic number.

It is not a de Polignac number, because 6605500021 - 2¹⁹ = 6604975733 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6605500061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3302750010 + 3302750011.

It is an arithmetic number, because the mean of its divisors is an integer number (3302750011).

Almost surely, 2^6605500021 is an apocalyptic number.

It is an amenable number.

6605500021 is a deficient number, since it is larger than the sum of its proper divisors (1).

6605500021 is an equidigital number, since it uses as much as digits as its factorization.

6605500021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1800, while the sum is 25.

The square root of 6605500021 is about 81274.2272863913. The cubic root of 6605500021 is about 1876.2983619795.

Adding to 6605500021 its reverse (1200055066), we get a palindrome (7805555087).

The spelling of 6605500021 in words is "six billion, six hundred five million, five hundred thousand, twenty-one".