6644121725 has 6 divisors (see below), whose sum is σ = 8238710970. Its totient is φ = 5315297360.

The previous prime is 6644121721. The next prime is 6644121727. The reversal of 6644121725 is 5271214466.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 209033764 + 6435087961 = 14458^2 + 80219^2 .

It is not a de Polignac number, because 6644121725 - 2² = 6644121721 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6644121721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 132882410 + ... + 132882459.

It is an arithmetic number, because the mean of its divisors is an integer number (1373118495).

Almost surely, 2^6644121725 is an apocalyptic number.

It is an amenable number.

6644121725 is a deficient number, since it is larger than the sum of its proper divisors (1594589245).

6644121725 is a wasteful number, since it uses less digits than its factorization.

6644121725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265764879 (or 265764874 counting only the distinct ones).

The product of its digits is 80640, while the sum is 38.

The square root of 6644121725 is about 81511.4821666248. The cubic root of 6644121725 is about 1879.9481014985.

The spelling of 6644121725 in words is "six billion, six hundred forty-four million, one hundred twenty-one thousand, seven hundred twenty-five".