8401721 has 2 divisors, whose sum is σ = 8401722. Its totient is φ = 8401720.

The previous prime is 8401717. The next prime is 8401741. The reversal of 8401721 is 1271048.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4791721 + 3610000 = 2189^2 + 1900^2 .

It is a cyclic number.

It is not a de Polignac number, because 8401721 - 2² = 8401717 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a plaindrome in base 14.

It is not a weakly prime, because it can be changed into another prime (8401741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4200860 + 4200861.

It is an arithmetic number, because the mean of its divisors is an integer number (4200861).

Almost surely, 2^8401721 is an apocalyptic number.

It is an amenable number.

8401721 is a deficient number, since it is larger than the sum of its proper divisors (1).

8401721 is an equidigital number, since it uses as much as digits as its factorization.

8401721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 448, while the sum is 23.

The square root of 8401721 is about 2898.5722347390. The cubic root of 8401721 is about 203.2931530986.

Adding to 8401721 its reverse (1271048), we get a palindrome (9672769).

The spelling of 8401721 in words is "eight million, four hundred one thousand, seven hundred twenty-one".