21075552 has 120 divisors (see below), whose sum is σ = 63667296. Its totient is φ = 6835968.

The previous prime is 21075497. The next prime is 21075559. The reversal of 21075552 is 25557012.

It is a happy number.

21075552 is a `hidden beast` number, since 2 + 107 + 5 + 552 = 666.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21075559) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 121738 + ... + 121910.

Almost surely, 2^21075552 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 21075552, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31833648).

21075552 is an abundant number, since it is smaller than the sum of its proper divisors (42591744).

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

21075552 is a wasteful number, since it uses less digits than its factorization.

21075552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 242 (or 225 counting only the distinct ones).

The product of its (nonzero) digits is 3500, while the sum is 27.

The square root of 21075552 is about 4590.8116929362. The cubic root of 21075552 is about 276.2228823459. Note that the first 3 decimals are identical.

The spelling of 21075552 in words is "twenty-one million, seventy-five thousand, five hundred fifty-two".