6726991621 has 16 divisors (see below), whose sum is σ = 7719653376. Its totient is φ = 5742290736.

The previous prime is 6726991589. The next prime is 6726991633. The reversal of 6726991621 is 1261996276.

It is a happy number.

It is not a de Polignac number, because 6726991621 - 2⁵ = 6726991589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6726991651) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3222240 + ... + 3224326.

It is an arithmetic number, because the mean of its divisors is an integer number (482478336).

Almost surely, 2^6726991621 is an apocalyptic number.

It is an amenable number.

6726991621 is a deficient number, since it is larger than the sum of its proper divisors (992661755).

6726991621 is a wasteful number, since it uses less digits than its factorization.

6726991621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3768.

The product of its digits is 489888, while the sum is 49.

The square root of 6726991621 is about 82018.2395629167. The cubic root of 6726991621 is about 1887.7318162482.

The spelling of 6726991621 in words is "six billion, seven hundred twenty-six million, nine hundred ninety-one thousand, six hundred twenty-one".