21525756 has 48 divisors (see below), whose sum is σ = 57953280. Its totient is φ = 6091200.

The previous prime is 21525733. The next prime is 21525767. The reversal of 21525756 is 65752512.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 7981 + ... + 10331.

It is an arithmetic number, because the mean of its divisors is an integer number (1207360).

Almost surely, 2^21525756 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 21525756, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28976640).

21525756 is an abundant number, since it is smaller than the sum of its proper divisors (36427524).

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

21525756 is a wasteful number, since it uses less digits than its factorization.

21525756 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2474 (or 2472 counting only the distinct ones).

The product of its digits is 21000, while the sum is 33.

The square root of 21525756 is about 4639.5857573710. The cubic root of 21525756 is about 278.1758802844.

The spelling of 21525756 in words is "twenty-one million, five hundred twenty-five thousand, seven hundred fifty-six".