19998397 has 4 divisors (see below), whose sum is σ = 20463520. Its totient is φ = 19533276.

The previous prime is 19998383. The next prime is 19998403. The reversal of 19998397 is 79389991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 19998397 - 2²³ = 11609789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19998337) 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 in 3 ways as a sum of consecutive naturals, for example, 232497 + ... + 232582.

It is an arithmetic number, because the mean of its divisors is an integer number (5115880).

Almost surely, 2^19998397 is an apocalyptic number.

It is an amenable number.

19998397 is a deficient number, since it is larger than the sum of its proper divisors (465123).

19998397 is an equidigital number, since it uses as much as digits as its factorization.

19998397 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 465122.

The product of its digits is 1102248, while the sum is 55.

The square root of 19998397 is about 4471.9567305599. The cubic root of 19998397 is about 271.4345094467.

It can be divided in two parts, 199 and 98397, that added together give a square (98596 = 314²).

The spelling of 19998397 in words is "nineteen million, nine hundred ninety-eight thousand, three hundred ninety-seven".