21389368 has 64 divisors (see below), whose sum is σ = 53867520. Its totient is φ = 7689600.

The previous prime is 21389363. The next prime is 21389377. The reversal of 21389368 is 86398312.

It is a self number, because there is not a number n which added to its sum of digits gives 21389368.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21389363) 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, 6673 + ... + 9343.

It is an arithmetic number, because the mean of its divisors is an integer number (841680).

Almost surely, 2^21389368 is an apocalyptic number.

21389368 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21389368, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26933760).

21389368 is an abundant number, since it is smaller than the sum of its proper divisors (32478152).

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

21389368 is a wasteful number, since it uses less digits than its factorization.

21389368 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2708 (or 2704 counting only the distinct ones).

The product of its digits is 62208, while the sum is 40.

The square root of 21389368 is about 4624.8641061117. The cubic root of 21389368 is about 277.5871241194.

The spelling of 21389368 in words is "twenty-one million, three hundred eighty-nine thousand, three hundred sixty-eight".