19999729 has 2 divisors, whose sum is σ = 19999730. Its totient is φ = 19999728.

The previous prime is 19999697. The next prime is 19999739. The reversal of 19999729 is 92799991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19936225 + 63504 = 4465^2 + 252^2 .

It is a cyclic number.

It is not a de Polignac number, because 19999729 - 2⁵ = 19999697 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19999729.

It is not a weakly prime, because it can be changed into another prime (19999739) 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, 9999864 + 9999865.

It is an arithmetic number, because the mean of its divisors is an integer number (9999865).

Almost surely, 2^19999729 is an apocalyptic number.

It is an amenable number.

19999729 is a deficient number, since it is larger than the sum of its proper divisors (1).

19999729 is an equidigital number, since it uses as much as digits as its factorization.

19999729 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 826686, while the sum is 55.

The square root of 19999729 is about 4472.1056561758. The cubic root of 19999729 is about 271.4405356420.

The spelling of 19999729 in words is "nineteen million, nine hundred ninety-nine thousand, seven hundred twenty-nine".