6561187573 has 4 divisors (see below), whose sum is σ = 6628828780. Its totient is φ = 6493546368.

The previous prime is 6561187547. The next prime is 6561187583. The reversal of 6561187573 is 3757811656.

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 4425176484 + 2136011089 = 66522^2 + 46217^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6561187573 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6561187543) 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, 33820458 + ... + 33820651.

It is an arithmetic number, because the mean of its divisors is an integer number (1657207195).

Almost surely, 2^6561187573 is an apocalyptic number.

It is an amenable number.

6561187573 is a deficient number, since it is larger than the sum of its proper divisors (67641207).

6561187573 is an equidigital number, since it uses as much as digits as its factorization.

6561187573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67641206.

The product of its digits is 1058400, while the sum is 49.

The square root of 6561187573 is about 81001.1578497493. The cubic root of 6561187573 is about 1872.0932808859.

The spelling of 6561187573 in words is "six billion, five hundred sixty-one million, one hundred eighty-seven thousand, five hundred seventy-three".