6561320271 has 8 divisors (see below), whose sum is σ = 9543738624. Its totient is φ = 3976557720.

The previous prime is 6561320261. The next prime is 6561320327. The reversal of 6561320271 is 1720231656.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 6561320271 - 2¹⁴ = 6561303887 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 198827887 = 6561320271 / (6 + 5 + 6 + 1 + 3 + 2 + 0 + 2 + 7 + 1).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6561320201) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 99413911 + ... + 99413976.

It is an arithmetic number, because the mean of its divisors is an integer number (1192967328).

Almost surely, 2^6561320271 is an apocalyptic number.

6561320271 is a deficient number, since it is larger than the sum of its proper divisors (2982418353).

6561320271 is a wasteful number, since it uses less digits than its factorization.

6561320271 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198827901.

The product of its (nonzero) digits is 15120, while the sum is 33.

The square root of 6561320271 is about 81001.9769573558. The cubic root of 6561320271 is about 1872.1059016377.

The spelling of 6561320271 in words is "six billion, five hundred sixty-one million, three hundred twenty thousand, two hundred seventy-one".