6561665015 has 16 divisors (see below), whose sum is σ = 8437631328. Its totient is φ = 4881017856.

The previous prime is 6561664957. The next prime is 6561665017. The reversal of 6561665015 is 5105661656.

It is a cyclic number.

It is not a de Polignac number, because 6561665015 - 2¹⁸ = 6561402871 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 (6561665017) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 457982 + ... + 472091.

It is an arithmetic number, because the mean of its divisors is an integer number (527351958).

Almost surely, 2^6561665015 is an apocalyptic number.

6561665015 is a deficient number, since it is larger than the sum of its proper divisors (1875966313).

6561665015 is a wasteful number, since it uses less digits than its factorization.

6561665015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 930178.

The product of its (nonzero) digits is 162000, while the sum is 41.

The square root of 6561665015 is about 81004.1049268492. The cubic root of 6561665015 is about 1872.1386890416.

The spelling of 6561665015 in words is "six billion, five hundred sixty-one million, six hundred sixty-five thousand, fifteen".