21647648 has 48 divisors (see below), whose sum is σ = 47083680. Its totient is φ = 9715200.

The previous prime is 21647629. The next prime is 21647653. The reversal of 21647648 is 84674612.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30983 + ... + 31673.

It is an arithmetic number, because the mean of its divisors is an integer number (980910).

Almost surely, 2^21647648 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 21647648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23541840).

21647648 is an abundant number, since it is smaller than the sum of its proper divisors (25436032).

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

21647648 is a wasteful number, since it uses less digits than its factorization.

21647648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 801 (or 793 counting only the distinct ones).

The product of its digits is 64512, while the sum is 38.

The square root of 21647648 is about 4652.7033002331. The cubic root of 21647648 is about 278.6999596474.

The spelling of 21647648 in words is "twenty-one million, six hundred forty-seven thousand, six hundred forty-eight".