6561667521565 has 32 divisors (see below), whose sum is σ = 8989571033856. Its totient is φ = 4554883445760.

The previous prime is 6561667521551. The next prime is 6561667521593. The reversal of 6561667521565 is 5651257661656.

It is not a de Polignac number, because 6561667521565 - 2¹⁷ = 6561667390493 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2764857 + ... + 4557166.

It is an arithmetic number, because the mean of its divisors is an integer number (280924094808).

Almost surely, 2^{6561667521565} is an apocalyptic number.

6561667521565 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

6561667521565 is a deficient number, since it is larger than the sum of its proper divisors (2427903512291).

6561667521565 is a wasteful number, since it uses less digits than its factorization.

6561667521565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7322869.

The product of its digits is 68040000, while the sum is 61.

The spelling of 6561667521565 in words is "six trillion, five hundred sixty-one billion, six hundred sixty-seven million, five hundred twenty-one thousand, five hundred sixty-five".