21998808 has 96 divisors (see below), whose sum is σ = 67594800. Its totient is φ = 6407424.

The previous prime is 21998803. The next prime is 21998819. The reversal of 21998808 is 80889912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21998803) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 17166 + ... + 18402.

Almost surely, 2^21998808 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21998808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33797400).

21998808 is an abundant number, since it is smaller than the sum of its proper divisors (45595992).

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

21998808 is a wasteful number, since it uses less digits than its factorization.

21998808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1281 (or 1274 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 45.

The square root of 21998808 is about 4690.2886904752. The cubic root of 21998808 is about 280.1988723213.

The spelling of 21998808 in words is "twenty-one million, nine hundred ninety-eight thousand, eight hundred eight".