21765168 has 90 divisors (see below), whose sum is σ = 64829804. Its totient is φ = 6815232.

The previous prime is 21765157. The next prime is 21765187. The reversal of 21765168 is 86156712.

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

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 41355 + ... + 41877.

Almost surely, 2^21765168 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 21765168, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32414902).

21765168 is an abundant number, since it is smaller than the sum of its proper divisors (43064636).

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

21765168 is a wasteful number, since it uses less digits than its factorization.

21765168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 571 (or 545 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 21765168 is about 4665.3154234199. The cubic root of 21765168 is about 279.2033819783.

The spelling of 21765168 in words is "twenty-one million, seven hundred sixty-five thousand, one hundred sixty-eight".