19997239 has 4 divisors (see below), whose sum is σ = 20043856. Its totient is φ = 19950624.

The previous prime is 19997227. The next prime is 19997251. The reversal of 19997239 is 93279991.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (19997227) and next prime (19997251).

It is a cyclic number.

It is not a de Polignac number, because 19997239 - 2¹⁵ = 19964471 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19997192 and 19997201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19997209) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22659 + ... + 23524.

It is an arithmetic number, because the mean of its divisors is an integer number (5010964).

Almost surely, 2^19997239 is an apocalyptic number.

19997239 is a deficient number, since it is larger than the sum of its proper divisors (46617).

19997239 is an equidigital number, since it uses as much as digits as its factorization.

19997239 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46616.

The product of its digits is 275562, while the sum is 49.

The square root of 19997239 is about 4471.8272551609. The cubic root of 19997239 is about 271.4292702396.

The spelling of 19997239 in words is "nineteen million, nine hundred ninety-seven thousand, two hundred thirty-nine".