6551991556 has 24 divisors (see below), whose sum is σ = 13244134176. Its totient is φ = 2802990720.

The previous prime is 6551991533. The next prime is 6551991581.

6551991556 is nontrivially palindromic in base 10.

It is a super-2 number, since 2×6551991556² = 85857186699790602272, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4378926 + ... + 4380421.

It is an arithmetic number, because the mean of its divisors is an integer number (551838924).

Almost surely, 2^6551991556 is an apocalyptic number.

It is an amenable number.

6551991556 is an abundant number, since it is smaller than the sum of its proper divisors (6692142620).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

6551991556 is a wasteful number, since it uses less digits than its factorization.

6551991556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8759379 (or 8759377 counting only the distinct ones).

The product of its digits is 1822500, while the sum is 52.

The square root of 6551991556 is about 80944.3732201319. The cubic root of 6551991556 is about 1871.2182436151.

The spelling of 6551991556 in words is "six billion, five hundred fifty-one million, nine hundred ninety-one thousand, five hundred fifty-six".