19998247 has 4 divisors (see below), whose sum is σ = 20867760. Its totient is φ = 19128736.

The previous prime is 19998229. The next prime is 19998263. The reversal of 19998247 is 74289991.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19998247 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 19998247.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19998217) 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, 434722 + ... + 434767.

It is an arithmetic number, because the mean of its divisors is an integer number (5216940).

Almost surely, 2^19998247 is an apocalyptic number.

19998247 is a deficient number, since it is larger than the sum of its proper divisors (869513).

19998247 is an equidigital number, since it uses as much as digits as its factorization.

19998247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 869512.

The product of its digits is 326592, while the sum is 49.

The square root of 19998247 is about 4471.9399593465. The cubic root of 19998247 is about 271.4338308043.

The spelling of 19998247 in words is "nineteen million, nine hundred ninety-eight thousand, two hundred forty-seven".