21506752 has 28 divisors (see below), whose sum is σ = 43287696. Its totient is φ = 10599680.

The previous prime is 21506729. The next prime is 21506753. The reversal of 21506752 is 25760512.

It is a self number, because there is not a number n which added to its sum of digits gives 21506752.

It is not an unprimeable number, because it can be changed into a prime (21506753) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2178 + ... + 6910.

Almost surely, 2^21506752 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 21506752, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21643848).

21506752 is an abundant number, since it is smaller than the sum of its proper divisors (21780944).

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

21506752 is an equidigital number, since it uses as much as digits as its factorization.

21506752 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4816 (or 4806 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 28.

The square root of 21506752 is about 4637.5372774782. The cubic root of 21506752 is about 278.0939937155.

The spelling of 21506752 in words is "twenty-one million, five hundred six thousand, seven hundred fifty-two".