6931721 has 2 divisors, whose sum is σ = 6931722. Its totient is φ = 6931720.

The previous prime is 6931679. The next prime is 6931723. The reversal of 6931721 is 1271396.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5953600 + 978121 = 2440^2 + 989^2 .

It is a cyclic number.

It is not a de Polignac number, because 6931721 - 2⁶ = 6931657 is a prime.

Together with 6931723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (6931723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3465860 + 3465861.

It is an arithmetic number, because the mean of its divisors is an integer number (3465861).

Almost surely, 2^6931721 is an apocalyptic number.

It is an amenable number.

6931721 is a deficient number, since it is larger than the sum of its proper divisors (1).

6931721 is an equidigital number, since it uses as much as digits as its factorization.

6931721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2268, while the sum is 29.

The square root of 6931721 is about 2632.8161728461. The cubic root of 6931721 is about 190.6691181949.

The spelling of 6931721 in words is "six million, nine hundred thirty-one thousand, seven hundred twenty-one".