21768912 has 120 divisors (see below), whose sum is σ = 69058080. Its totient is φ = 6583680.

The previous prime is 21768911. The next prime is 21768917. The reversal of 21768912 is 21986712.

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 (21768911) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 42514 + ... + 43022.

It is an arithmetic number, because the mean of its divisors is an integer number (575484).

Almost surely, 2^21768912 is an apocalyptic number.

21768912 is a gapful number since it is divisible by the number (22) 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 21768912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34529040).

21768912 is an abundant number, since it is smaller than the sum of its proper divisors (47289168).

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

21768912 is a wasteful number, since it uses less digits than its factorization.

21768912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 543 (or 525 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 21768912 is about 4665.7166652080. The cubic root of 21768912 is about 279.2193903934.

The spelling of 21768912 in words is "twenty-one million, seven hundred sixty-eight thousand, nine hundred twelve".