21521248 has 48 divisors (see below), whose sum is σ = 50107680. Its totient is φ = 8902656.

The previous prime is 21521183. The next prime is 21521249. The reversal of 21521248 is 84212512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21521249) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4840 + ... + 8152.

It is an arithmetic number, because the mean of its divisors is an integer number (1043910).

Almost surely, 2^21521248 is an apocalyptic number.

21521248 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 21521248, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25053840).

21521248 is an abundant number, since it is smaller than the sum of its proper divisors (28586432).

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

21521248 is a wasteful number, since it uses less digits than its factorization.

21521248 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3359 (or 3351 counting only the distinct ones).

The product of its digits is 1280, while the sum is 25.

The square root of 21521248 is about 4639.0999126986. The cubic root of 21521248 is about 278.1564600696.

The spelling of 21521248 in words is "twenty-one million, five hundred twenty-one thousand, two hundred forty-eight".