21506748 has 48 divisors (see below), whose sum is σ = 54190080. Its totient is φ = 6618304.

The previous prime is 21506729. The next prime is 21506753. The reversal of 21506748 is 84760512.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6661 + ... + 9347.

It is an arithmetic number, because the mean of its divisors is an integer number (1128960).

Almost surely, 2^21506748 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 21506748, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27095040).

21506748 is an abundant number, since it is smaller than the sum of its proper divisors (32683332).

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

21506748 is a wasteful number, since it uses less digits than its factorization.

21506748 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2746 (or 2744 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 21506748 is about 4637.5368462148. The cubic root of 21506748 is about 278.0939764748.

The spelling of 21506748 in words is "twenty-one million, five hundred six thousand, seven hundred forty-eight".