6681631921 has 4 divisors (see below), whose sum is σ = 6695939952. Its totient is φ = 6667323892.

The previous prime is 6681631919. The next prime is 6681631933. The reversal of 6681631921 is 1291361866.

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 6681631921 - 2¹ = 6681631919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6681631961) 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, 7153315 + ... + 7154248.

It is an arithmetic number, because the mean of its divisors is an integer number (1673984988).

Almost surely, 2^6681631921 is an apocalyptic number.

It is an amenable number.

6681631921 is a deficient number, since it is larger than the sum of its proper divisors (14308031).

6681631921 is a wasteful number, since it uses less digits than its factorization.

6681631921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14308030.

The product of its digits is 93312, while the sum is 43.

The square root of 6681631921 is about 81741.2498130534. The cubic root of 6681631921 is about 1883.4792896585.

The spelling of 6681631921 in words is "six billion, six hundred eighty-one million, six hundred thirty-one thousand, nine hundred twenty-one".