6541471721 has 4 divisors (see below), whose sum is σ = 6718268292. Its totient is φ = 6364675152.

The previous prime is 6541471687. The next prime is 6541471733. The reversal of 6541471721 is 1271741456.

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 4134490000 + 2406981721 = 64300^2 + 49061^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6541471721 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6541473721) 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, 88398230 + ... + 88398303.

It is an arithmetic number, because the mean of its divisors is an integer number (1679567073).

Almost surely, 2^6541471721 is an apocalyptic number.

It is an amenable number.

6541471721 is a deficient number, since it is larger than the sum of its proper divisors (176796571).

6541471721 is a wasteful number, since it uses less digits than its factorization.

6541471721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 176796570.

The product of its digits is 47040, while the sum is 38.

The square root of 6541471721 is about 80879.3652361342. The cubic root of 6541471721 is about 1870.2162352064.

The spelling of 6541471721 in words is "six billion, five hundred forty-one million, four hundred seventy-one thousand, seven hundred twenty-one".