21669888 has 48 divisors (see below), whose sum is σ = 57788640. Its totient is φ = 7221248.

The previous prime is 21669871. The next prime is 21669943. The reversal of 21669888 is 88896612.

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

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4381 + ... + 7907.

It is an arithmetic number, because the mean of its divisors is an integer number (1203930).

Almost surely, 2^21669888 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 21669888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28894320).

21669888 is an abundant number, since it is smaller than the sum of its proper divisors (36118752).

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

21669888 is an equidigital number, since it uses as much as digits as its factorization.

21669888 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3552 (or 3532 counting only the distinct ones).

The product of its digits is 331776, while the sum is 48.

The square root of 21669888 is about 4655.0926951029. The cubic root of 21669888 is about 278.7953690222.

The spelling of 21669888 in words is "twenty-one million, six hundred sixty-nine thousand, eight hundred eighty-eight".