21928648 has 32 divisors (see below), whose sum is σ = 47793600. Its totient is φ = 9237312.

The previous prime is 21928639. The next prime is 21928663. The reversal of 21928648 is 84682912.

It is a self number, because there is not a number n which added to its sum of digits gives 21928648.

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, 15 + ... + 6622.

It is an arithmetic number, because the mean of its divisors is an integer number (1493550).

Almost surely, 2^21928648 is an apocalyptic number.

21928648 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21928648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23896800).

21928648 is an abundant number, since it is smaller than the sum of its proper divisors (25864952).

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

21928648 is a wasteful number, since it uses less digits than its factorization.

21928648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6709 (or 6705 counting only the distinct ones).

The product of its digits is 55296, while the sum is 40.

The square root of 21928648 is about 4682.8034338417. The cubic root of 21928648 is about 279.9006790590.

It can be divided in two parts, 2 and 1928648, that multiplied together give a square (3857296 = 1964²).

The spelling of 21928648 in words is "twenty-one million, nine hundred twenty-eight thousand, six hundred forty-eight".