6721111421 has 4 divisors (see below), whose sum is σ = 6722699712. Its totient is φ = 6719523132.

The previous prime is 6721111409. The next prime is 6721111447. The reversal of 6721111421 is 1241111276.

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 6721111421 - 2²² = 6716917117 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 (6721111121) 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, 787781 + ... + 796266.

It is an arithmetic number, because the mean of its divisors is an integer number (1680674928).

Almost surely, 2^6721111421 is an apocalyptic number.

It is an amenable number.

6721111421 is a deficient number, since it is larger than the sum of its proper divisors (1588291).

6721111421 is a wasteful number, since it uses less digits than its factorization.

6721111421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1588290.

The product of its digits is 672, while the sum is 26.

The square root of 6721111421 is about 81982.3848213749. The cubic root of 6721111421 is about 1887.1816209981.

Adding to 6721111421 its reverse (1241111276), we get a palindrome (7962222697).

The spelling of 6721111421 in words is "six billion, seven hundred twenty-one million, one hundred eleven thousand, four hundred twenty-one".