6561500405 has 4 divisors (see below), whose sum is σ = 7873800492. Its totient is φ = 5249200320.

The previous prime is 6561500401. The next prime is 6561500411. The reversal of 6561500405 is 5040051656.

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 1858558321 + 4702942084 = 43111^2 + 68578^2 .

It is not a de Polignac number, because 6561500405 - 2² = 6561500401 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 (6561500401) 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, 656150036 + ... + 656150045.

It is an arithmetic number, because the mean of its divisors is an integer number (1968450123).

Almost surely, 2^6561500405 is an apocalyptic number.

It is an amenable number.

6561500405 is a deficient number, since it is larger than the sum of its proper divisors (1312300087).

6561500405 is a wasteful number, since it uses less digits than its factorization.

6561500405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1312300086.

The product of its (nonzero) digits is 18000, while the sum is 32.

The square root of 6561500405 is about 81003.0888608576. The cubic root of 6561500405 is about 1872.1230336998.

The spelling of 6561500405 in words is "six billion, five hundred sixty-one million, five hundred thousand, four hundred five".