6644800081 has 4 divisors (see below), whose sum is σ = 7035670692. Its totient is φ = 6253929472.

The previous prime is 6644800079. The next prime is 6644800087. The reversal of 6644800081 is 1800084466.

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 4001195025 + 2643605056 = 63255^2 + 51416^2 .

It is a cyclic number.

It is not a de Polignac number, because 6644800081 - 2¹ = 6644800079 is a prime.

It is a super-2 number, since 2×6644800081² = 88306736232915213122, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 6644800081.

It is not an unprimeable number, because it can be changed into a prime (6644800087) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 195435280 + ... + 195435313.

It is an arithmetic number, because the mean of its divisors is an integer number (1758917673).

Almost surely, 2^6644800081 is an apocalyptic number.

It is an amenable number.

6644800081 is a deficient number, since it is larger than the sum of its proper divisors (390870611).

6644800081 is a wasteful number, since it uses less digits than its factorization.

6644800081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 390870610.

The product of its (nonzero) digits is 36864, while the sum is 37.

The square root of 6644800081 is about 81515.6431674314. The cubic root of 6644800081 is about 1880.0120793890.

The spelling of 6644800081 in words is "six billion, six hundred forty-four million, eight hundred thousand, eighty-one".