19897729 has 2 divisors, whose sum is σ = 19897730. Its totient is φ = 19897728.

The previous prime is 19897699. The next prime is 19897733. The reversal of 19897729 is 92779891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19158129 + 739600 = 4377^2 + 860^2 .

It is a cyclic number.

It is not a de Polignac number, because 19897729 - 2¹³ = 19889537 is a prime.

It is not a weakly prime, because it can be changed into another prime (19897789) 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, 9948864 + 9948865.

It is an arithmetic number, because the mean of its divisors is an integer number (9948865).

Almost surely, 2^19897729 is an apocalyptic number.

It is an amenable number.

19897729 is a deficient number, since it is larger than the sum of its proper divisors (1).

19897729 is an equidigital number, since it uses as much as digits as its factorization.

19897729 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 571536, while the sum is 52.

The square root of 19897729 is about 4460.6870547036. The cubic root of 19897729 is about 270.9782937640.

The spelling of 19897729 in words is "nineteen million, eight hundred ninety-seven thousand, seven hundred twenty-nine".