19947439 has 2 divisors, whose sum is σ = 19947440. Its totient is φ = 19947438.

The previous prime is 19947437. The next prime is 19947457. The reversal of 19947439 is 93474991.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 19947439 - 2¹ = 19947437 is a prime.

Together with 19947437, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19947437) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9973719 + 9973720.

It is an arithmetic number, because the mean of its divisors is an integer number (9973720).

Almost surely, 2^19947439 is an apocalyptic number.

19947439 is a deficient number, since it is larger than the sum of its proper divisors (1).

19947439 is an equidigital number, since it uses as much as digits as its factorization.

19947439 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 244944, while the sum is 46.

The square root of 19947439 is about 4466.2555905367. The cubic root of 19947439 is about 271.2037655418.

The spelling of 19947439 in words is "nineteen million, nine hundred forty-seven thousand, four hundred thirty-nine".