6644820881 has 2 divisors, whose sum is σ = 6644820882. Its totient is φ = 6644820880.

The previous prime is 6644820857. The next prime is 6644820883. The reversal of 6644820881 is 1880284466.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5529260881 + 1115560000 = 74359^2 + 33400^2 .

It is a cyclic number.

It is not a de Polignac number, because 6644820881 - 2⁶ = 6644820817 is a prime.

It is a super-2 number, since 2×6644820881² = 88307289081147232322, which contains 22 as substring.

Together with 6644820883, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (6644820883) 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 as a sum of consecutive naturals, namely, 3322410440 + 3322410441.

It is an arithmetic number, because the mean of its divisors is an integer number (3322410441).

Almost surely, 2^6644820881 is an apocalyptic number.

It is an amenable number.

6644820881 is a deficient number, since it is larger than the sum of its proper divisors (1).

6644820881 is an equidigital number, since it uses as much as digits as its factorization.

6644820881 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 589824, while the sum is 47.

The square root of 6644820881 is about 81515.7707502051. The cubic root of 6644820881 is about 1880.0140410337.

The spelling of 6644820881 in words is "six billion, six hundred forty-four million, eight hundred twenty thousand, eight hundred eighty-one".