6561808131 has 4 divisors (see below), whose sum is σ = 8749077512. Its totient is φ = 4374538752.

The previous prime is 6561808129. The next prime is 6561808147. The reversal of 6561808131 is 1318081656.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 6561808131 - 2¹ = 6561808129 is a prime.

It is a super-2 number, since 2×6561808131² = 86114651896115426322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 6561808131.

It is not an unprimeable number, because it can be changed into a prime (6561808111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1093634686 + ... + 1093634691.

It is an arithmetic number, because the mean of its divisors is an integer number (2187269378).

Almost surely, 2^6561808131 is an apocalyptic number.

6561808131 is a deficient number, since it is larger than the sum of its proper divisors (2187269381).

6561808131 is a wasteful number, since it uses less digits than its factorization.

6561808131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2187269380.

The product of its (nonzero) digits is 34560, while the sum is 39.

The square root of 6561808131 is about 81004.9883093628. The cubic root of 6561808131 is about 1872.1522999698.

Adding to 6561808131 its reverse (1318081656), we get a palindrome (7879889787).

The spelling of 6561808131 in words is "six billion, five hundred sixty-one million, eight hundred eight thousand, one hundred thirty-one".