6544985661 has 12 divisors (see below), whose sum is σ = 9459793980. Its totient is φ = 4360588800.

The previous prime is 6544985653. The next prime is 6544985683. The reversal of 6544985661 is 1665894456.

6544985661 is a `hidden beast` number, since 6 + 544 + 98 + 5 + 6 + 6 + 1 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 6428992761 + 115992900 = 80181^2 + 10770^2 .

It is not a de Polignac number, because 6544985661 - 2³ = 6544985653 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 6544985598 and 6544985607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6544985621) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 212706 + ... + 241523.

It is an arithmetic number, because the mean of its divisors is an integer number (788316165).

Almost surely, 2^6544985661 is an apocalyptic number.

It is an amenable number.

6544985661 is a deficient number, since it is larger than the sum of its proper divisors (2914808319).

6544985661 is a wasteful number, since it uses less digits than its factorization.

6544985661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 455836 (or 455833 counting only the distinct ones).

The product of its digits is 6220800, while the sum is 54.

The square root of 6544985661 is about 80901.0856602061. The cubic root of 6544985661 is about 1870.5510554385.

The spelling of 6544985661 in words is "six billion, five hundred forty-four million, nine hundred eighty-five thousand, six hundred sixty-one".