19991338 has 4 divisors (see below), whose sum is σ = 29987010. Its totient is φ = 9995668.

The previous prime is 19991333. The next prime is 19991339. The reversal of 19991338 is 83319991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 83319991 = 71 ⋅1173521.

It can be written as a sum of positive squares in only one way, i.e., 19954089 + 37249 = 4467^2 + 193^2 .

It is a junction number, because it is equal to n+sod(n) for n = 19991294 and 19991303.

It is not an unprimeable number, because it can be changed into a prime (19991333) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4997833 + ... + 4997836.

Almost surely, 2^19991338 is an apocalyptic number.

19991338 is a deficient number, since it is larger than the sum of its proper divisors (9995672).

19991338 is an equidigital number, since it uses as much as digits as its factorization.

19991338 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9995671.

The product of its digits is 52488, while the sum is 43.

The square root of 19991338 is about 4471.1674090779. The cubic root of 19991338 is about 271.4025688585.

The spelling of 19991338 in words is "nineteen million, nine hundred ninety-one thousand, three hundred thirty-eight".