21255168 has 176 divisors, whose sum is σ = 67207104. Its totient is φ = 5898240.

The previous prime is 21255161. The next prime is 21255203. The reversal of 21255168 is 86155212.

It is a tau number, because it is divible by the number of its divisors (176).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21255161) 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, 574446 + ... + 574482.

Almost surely, 2^21255168 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 21255168, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33603552).

21255168 is an abundant number, since it is smaller than the sum of its proper divisors (45951936).

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

21255168 is a wasteful number, since it uses less digits than its factorization.

21255168 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88 (or 70 counting only the distinct ones).

The product of its digits is 4800, while the sum is 30.

The square root of 21255168 is about 4610.3327428723. The cubic root of 21255168 is about 277.0053650992.

The spelling of 21255168 in words is "twenty-one million, two hundred fifty-five thousand, one hundred sixty-eight".