21988368 has 80 divisors (see below), whose sum is σ = 65888640. Its totient is φ = 7007616.

The previous prime is 21988367. The next prime is 21988387. The reversal of 21988368 is 86388912.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (21988367) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8830 + ... + 11042.

It is an arithmetic number, because the mean of its divisors is an integer number (823608).

Almost surely, 2^21988368 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 21988368, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32944320).

21988368 is an abundant number, since it is smaller than the sum of its proper divisors (43900272).

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

21988368 is a wasteful number, since it uses less digits than its factorization.

21988368 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2253 (or 2241 counting only the distinct ones).

The product of its digits is 165888, while the sum is 45.

The square root of 21988368 is about 4689.1756205116. The cubic root of 21988368 is about 280.1545405390.

The spelling of 21988368 in words is "twenty-one million, nine hundred eighty-eight thousand, three hundred sixty-eight".