6381721688 has 8 divisors (see below), whose sum is σ = 11965728180. Its totient is φ = 3190860840.

The previous prime is 6381721609. The next prime is 6381721739. The reversal of 6381721688 is 8861271836.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 398857598 + ... + 398857613.

Almost surely, 2^6381721688 is an apocalyptic number.

It is an amenable number.

6381721688 is a deficient number, since it is larger than the sum of its proper divisors (5584006492).

6381721688 is a wasteful number, since it uses less digits than its factorization.

6381721688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 797715217 (or 797715213 counting only the distinct ones).

The product of its digits is 774144, while the sum is 50.

The square root of 6381721688 is about 79885.6788667406. The cubic root of 6381721688 is about 1854.8663395919.

The spelling of 6381721688 in words is "six billion, three hundred eighty-one million, seven hundred twenty-one thousand, six hundred eighty-eight".