1721364521 has 2 divisors, whose sum is σ = 1721364522. Its totient is φ = 1721364520.

The previous prime is 1721364509. The next prime is 1721364523. The reversal of 1721364521 is 1254631271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1602881296 + 118483225 = 40036^2 + 10885^2 .

It is a cyclic number.

It is not a de Polignac number, because 1721364521 - 2⁶ = 1721364457 is a prime.

Together with 1721364523, 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 (1721364523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860682260 + 860682261.

It is an arithmetic number, because the mean of its divisors is an integer number (860682261).

Almost surely, 2^1721364521 is an apocalyptic number.

It is an amenable number.

1721364521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1721364521 is an equidigital number, since it uses as much as digits as its factorization.

1721364521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10080, while the sum is 32.

The square root of 1721364521 is about 41489.3302066929. The cubic root of 1721364521 is about 1198.4620392300.

Adding to 1721364521 its reverse (1254631271), we get a palindrome (2975995792).

The spelling of 1721364521 in words is "one billion, seven hundred twenty-one million, three hundred sixty-four thousand, five hundred twenty-one".