6556999681 has 4 divisors (see below), whose sum is σ = 6561688000. Its totient is φ = 6552311364.

The previous prime is 6556999667. The next prime is 6556999711. The reversal of 6556999681 is 1869996556.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 6556999681 - 2²⁵ = 6523445249 is a prime.

It is a super-2 number, since 2×6556999681² = 85988489633268203522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6556999621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2342061 + ... + 2344858.

It is an arithmetic number, because the mean of its divisors is an integer number (1640422000).

Almost surely, 2^6556999681 is an apocalyptic number.

It is an amenable number.

6556999681 is a deficient number, since it is larger than the sum of its proper divisors (4688319).

6556999681 is a wasteful number, since it uses less digits than its factorization.

6556999681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4688318.

The product of its digits is 31492800, while the sum is 64.

The square root of 6556999681 is about 80975.3029077385. The cubic root of 6556999681 is about 1871.6948879095.

The spelling of 6556999681 in words is "six billion, five hundred fifty-six million, nine hundred ninety-nine thousand, six hundred eighty-one".