19998634 has 4 divisors (see below), whose sum is σ = 29997954. Its totient is φ = 9999316.

The previous prime is 19998617. The next prime is 19998637. The reversal of 19998634 is 43689991.

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

It can be written as a sum of positive squares in only one way, i.e., 10543009 + 9455625 = 3247^2 + 3075^2 .

It is a super-3 number, since 3×19998634³ (a number of 23 digits) contains 333 as substring.

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 not an unprimeable number, because it can be changed into a prime (19998637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4999657 + ... + 4999660.

Almost surely, 2^19998634 is an apocalyptic number.

19998634 is a deficient number, since it is larger than the sum of its proper divisors (9999320).

19998634 is an equidigital number, since it uses as much as digits as its factorization.

19998634 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9999319.

The product of its digits is 419904, while the sum is 49.

The square root of 19998634 is about 4471.9832289489. The cubic root of 19998634 is about 271.4355816947.

The spelling of 19998634 in words is "nineteen million, nine hundred ninety-eight thousand, six hundred thirty-four".