1721364509 has 2 divisors, whose sum is σ = 1721364510. Its totient is φ = 1721364508.

The previous prime is 1721364499. The next prime is 1721364521. The reversal of 1721364509 is 9054631271.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1648603609 + 72760900 = 40603^2 + 8530^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1721364509 is a prime.

It is a super-2 number, since 2×1721364509² = 5926191545689622162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1721364569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860682254 + 860682255.

It is an arithmetic number, because the mean of its divisors is an integer number (860682255).

Almost surely, 2^1721364509 is an apocalyptic number.

It is an amenable number.

1721364509 is a deficient number, since it is larger than the sum of its proper divisors (1).

1721364509 is an equidigital number, since it uses as much as digits as its factorization.

1721364509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 45360, while the sum is 38.

The square root of 1721364509 is about 41489.3300620774. The cubic root of 1721364509 is about 1198.4620364451.

The spelling of 1721364509 in words is "one billion, seven hundred twenty-one million, three hundred sixty-four thousand, five hundred nine".