21755328 has 56 divisors (see below), whose sum is σ = 65788032. Its totient is φ = 6215424.

The previous prime is 21755267. The next prime is 21755329. The reversal of 21755328 is 82355712.

It is a tau number, because it is divible by the number of its divisors (56).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21755329) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6750 + ... + 9437.

Almost surely, 2^21755328 is an apocalyptic number.

21755328 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21755328 is an abundant number, since it is smaller than the sum of its proper divisors (44032704).

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

21755328 is a wasteful number, since it uses less digits than its factorization.

21755328 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16209 (or 16199 counting only the distinct ones).

The product of its digits is 16800, while the sum is 33.

The square root of 21755328 is about 4664.2607131249. The cubic root of 21755328 is about 279.1612998250.

It can be divided in two parts, 2175 and 5328, that added together give a triangular number (7503 = T₁₂₂).

The spelling of 21755328 in words is "twenty-one million, seven hundred fifty-five thousand, three hundred twenty-eight".