6721718181 has 4 divisors (see below), whose sum is σ = 8962290912. Its totient is φ = 4481145452.

The previous prime is 6721718173. The next prime is 6721718221. The reversal of 6721718181 is 1818171276.

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 6721718181 - 2³ = 6721718173 is a prime.

It is a super-2 number, since 2×6721718181² = 90362990609571897522, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6721711181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1120286361 + ... + 1120286366.

It is an arithmetic number, because the mean of its divisors is an integer number (2240572728).

Almost surely, 2^6721718181 is an apocalyptic number.

It is an amenable number.

6721718181 is a deficient number, since it is larger than the sum of its proper divisors (2240572731).

6721718181 is a wasteful number, since it uses less digits than its factorization.

6721718181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2240572730.

The product of its digits is 37632, while the sum is 42.

The square root of 6721718181 is about 81986.0852889074. The cubic root of 6721718181 is about 1887.2384088214.

The spelling of 6721718181 in words is "six billion, seven hundred twenty-one million, seven hundred eighteen thousand, one hundred eighty-one".