21986688 has 64 divisors (see below), whose sum is σ = 60318720. Its totient is φ = 7088640.

The previous prime is 21986687. The next prime is 21986693. The reversal of 21986688 is 88668912.

It is a tau number, because it is divible by the number of its divisors (64).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21986683) 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, 10981 + ... + 12827.

It is an arithmetic number, because the mean of its divisors is an integer number (942480).

Almost surely, 2^21986688 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 21986688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30159360).

21986688 is an abundant number, since it is smaller than the sum of its proper divisors (38332032).

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

21986688 is a wasteful number, since it uses less digits than its factorization.

21986688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1895 (or 1883 counting only the distinct ones).

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

The square root of 21986688 is about 4688.9964811247. The cubic root of 21986688 is about 280.1474053783.

The spelling of 21986688 in words is "twenty-one million, nine hundred eighty-six thousand, six hundred eighty-eight".