21998868 has 24 divisors (see below), whose sum is σ = 52719072. Its totient is φ = 7134624.

The previous prime is 21998863. The next prime is 21998887. The reversal of 21998868 is 86889912.

It is a self number, because there is not a number n which added to its sum of digits gives 21998868.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21998863) 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 7 ways as a sum of consecutive naturals, for example, 24330 + ... + 25217.

It is an arithmetic number, because the mean of its divisors is an integer number (2196628).

Almost surely, 2^21998868 is an apocalyptic number.

It is an amenable number.

21998868 is an abundant number, since it is smaller than the sum of its proper divisors (30720204).

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

21998868 is a wasteful number, since it uses less digits than its factorization.

21998868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49591 (or 49589 counting only the distinct ones).

The product of its digits is 497664, while the sum is 51.

The square root of 21998868 is about 4690.2950866657. The cubic root of 21998868 is about 280.1991270611.

The spelling of 21998868 in words is "twenty-one million, nine hundred ninety-eight thousand, eight hundred sixty-eight".