1720399999 has 2 divisors, whose sum is σ = 1720400000. Its totient is φ = 1720399998.

The previous prime is 1720399997. The next prime is 1720400021. The reversal of 1720399999 is 9999930271.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1720399999 - 2¹ = 1720399997 is a prime.

Together with 1720399997, it forms a pair of twin primes.

1720399999 is a modest number, since divided by 99999 gives 17203 as remainder.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1720399997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860199999 + 860200000.

It is an arithmetic number, because the mean of its divisors is an integer number (860200000).

Almost surely, 2^1720399999 is an apocalyptic number.

1720399999 is a deficient number, since it is larger than the sum of its proper divisors (1).

1720399999 is an equidigital number, since it uses as much as digits as its factorization.

1720399999 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2480058, while the sum is 58.

The square root of 1720399999 is about 41477.7048424813. The cubic root of 1720399999 is about 1198.2381550271.

The spelling of 1720399999 in words is "one billion, seven hundred twenty million, three hundred ninety-nine thousand, nine hundred ninety-nine".