1721016721 has 2 divisors, whose sum is σ = 1721016722. Its totient is φ = 1721016720.

The previous prime is 1721016701. The next prime is 1721016793. The reversal of 1721016721 is 1276101271.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1624976721 + 96040000 = 40311^2 + 9800^2 .

It is a cyclic number.

It is not a de Polignac number, because 1721016721 - 2⁷ = 1721016593 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1721016721.

It is not a weakly prime, because it can be changed into another prime (1721016701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860508360 + 860508361.

It is an arithmetic number, because the mean of its divisors is an integer number (860508361).

Almost surely, 2^1721016721 is an apocalyptic number.

It is an amenable number.

1721016721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1721016721 is an equidigital number, since it uses as much as digits as its factorization.

1721016721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1176, while the sum is 28.

The square root of 1721016721 is about 41485.1385558732. The cubic root of 1721016721 is about 1198.3813177698.

Adding to 1721016721 its reverse (1276101271), we get a palindrome (2997117992).

The spelling of 1721016721 in words is "one billion, seven hundred twenty-one million, sixteen thousand, seven hundred twenty-one".