19998816 has 48 divisors (see below), whose sum is σ = 53787888. Its totient is φ = 6502400.

The previous prime is 19998809. The next prime is 19998841. The reversal of 19998816 is 61889991.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1396 + ... + 6476.

It is an arithmetic number, because the mean of its divisors is an integer number (1120581).

Almost surely, 2^19998816 is an apocalyptic number.

19998816 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19998816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26893944).

19998816 is an abundant number, since it is smaller than the sum of its proper divisors (33789072).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

19998816 is a wasteful number, since it uses less digits than its factorization.

19998816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5135 (or 5127 counting only the distinct ones).

The product of its digits is 279936, while the sum is 51.

The square root of 19998816 is about 4472.0035778161. The cubic root of 19998816 is about 271.4364051030.

The spelling of 19998816 in words is "nineteen million, nine hundred ninety-eight thousand, eight hundred sixteen".