6561155511 has 48 divisors (see below), whose sum is σ = 9864571392. Its totient is φ = 4199832000.

The previous prime is 6561155509. The next prime is 6561155527. The reversal of 6561155511 is 1155511656.

It is a happy number.

It is not a de Polignac number, because 6561155511 - 2¹ = 6561155509 is a prime.

It is a super-2 number, since 2×6561155511² = 86097523279051342242, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6561155551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5113276 + ... + 5114558.

It is an arithmetic number, because the mean of its divisors is an integer number (205511904).

Almost surely, 2^6561155511 is an apocalyptic number.

6561155511 is a deficient number, since it is larger than the sum of its proper divisors (3303415881).

6561155511 is a wasteful number, since it uses less digits than its factorization.

6561155511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1564 (or 1561 counting only the distinct ones).

The product of its digits is 22500, while the sum is 36.

The square root of 6561155511 is about 81000.9599387563. The cubic root of 6561155511 is about 1872.0902314810.

The spelling of 6561155511 in words is "six billion, five hundred sixty-one million, one hundred fifty-five thousand, five hundred eleven".