6561914865 has 16 divisors (see below), whose sum is σ = 11453524416. Its totient is φ = 3181534400.

The previous prime is 6561914857. The next prime is 6561914869. The reversal of 6561914865 is 5684191656.

It is not a de Polignac number, because 6561914865 - 2³ = 6561914857 is a prime.

It is not an unprimeable number, because it can be changed into a prime (6561914869) 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, 19884426 + ... + 19884755.

It is an arithmetic number, because the mean of its divisors is an integer number (715845276).

Almost surely, 2^6561914865 is an apocalyptic number.

It is an amenable number.

6561914865 is a deficient number, since it is larger than the sum of its proper divisors (4891609551).

6561914865 is a wasteful number, since it uses less digits than its factorization.

6561914865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39769200.

The product of its digits is 1555200, while the sum is 51.

The square root of 6561914865 is about 81005.6471179633. The cubic root of 6561914865 is about 1872.1624506892.

The spelling of 6561914865 in words is "six billion, five hundred sixty-one million, nine hundred fourteen thousand, eight hundred sixty-five".