21038688 has 144 divisors (see below), whose sum is σ = 67813200. Its totient is φ = 6128640.

The previous prime is 21038687. The next prime is 21038713. The reversal of 21038688 is 88683012.

It is a tau number, because it is divible by the number of its divisors (144).

It is a super-2 number, since 2×21038688² = 885252785522688, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21038683) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 91758 + ... + 91986.

It is an arithmetic number, because the mean of its divisors is an integer number (470925).

Almost surely, 2^21038688 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 21038688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33906600).

21038688 is an abundant number, since it is smaller than the sum of its proper divisors (46774512).

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

21038688 is a wasteful number, since it uses less digits than its factorization.

21038688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 285 (or 274 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 21038688 is about 4586.7949594461. The cubic root of 21038688 is about 276.0617379218.

The spelling of 21038688 in words is "twenty-one million, thirty-eight thousand, six hundred eighty-eight".