19997459 has 2 divisors, whose sum is σ = 19997460. Its totient is φ = 19997458.

The previous prime is 19997441. The next prime is 19997473. The reversal of 19997459 is 95479991.

It is a strong prime.

It is an emirp because it is prime and its reverse (95479991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19997459 - 2²⁰ = 18948883 is a prime.

It is a Sophie Germain prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19997459.

It is not a weakly prime, because it can be changed into another prime (19997489) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9998729 + 9998730.

It is an arithmetic number, because the mean of its divisors is an integer number (9998730).

Almost surely, 2^19997459 is an apocalyptic number.

19997459 is a deficient number, since it is larger than the sum of its proper divisors (1).

19997459 is an equidigital number, since it uses as much as digits as its factorization.

19997459 is an evil number, because the sum of its binary digits is even.

The product of its digits is 918540, while the sum is 53.

The square root of 19997459 is about 4471.8518535390. The cubic root of 19997459 is about 271.4302656140.

The spelling of 19997459 in words is "nineteen million, nine hundred ninety-seven thousand, four hundred fifty-nine".