6656444681 has 4 divisors (see below), whose sum is σ = 6656855700. Its totient is φ = 6656033664.

The previous prime is 6656444671. The next prime is 6656444689. The reversal of 6656444681 is 1864446566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1864446566 = 2 ⋅932223283.

It can be written as a sum of positive squares in 2 ways, for example, as 1338389056 + 5318055625 = 36584^2 + 72925^2 .

It is a cyclic number.

It is not a de Polignac number, because 6656444681 - 2²² = 6652250377 is a prime.

It is a super-2 number, since 2×6656444681² = 88616511582426383522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6656444689) 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, 180176 + ... + 213953.

It is an arithmetic number, because the mean of its divisors is an integer number (1664213925).

Almost surely, 2^6656444681 is an apocalyptic number.

It is an amenable number.

6656444681 is a deficient number, since it is larger than the sum of its proper divisors (411019).

6656444681 is a wasteful number, since it uses less digits than its factorization.

6656444681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 411018.

The product of its digits is 3317760, while the sum is 50.

The square root of 6656444681 is about 81587.0374569392. The cubic root of 6656444681 is about 1881.1096400234.

The spelling of 6656444681 in words is "six billion, six hundred fifty-six million, four hundred forty-four thousand, six hundred eighty-one".