21987648 has 84 divisors (see below), whose sum is σ = 64190880. Its totient is φ = 7193856.

The previous prime is 21987631. The next prime is 21987671. The reversal of 21987648 is 84678912.

It is a nialpdrome in base 12.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 33661 + ... + 34307.

Almost surely, 2^21987648 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 21987648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32095440).

21987648 is an abundant number, since it is smaller than the sum of its proper divisors (42203232).

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

21987648 is a wasteful number, since it uses less digits than its factorization.

21987648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 724 (or 711 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 21987648 is about 4689.0988473266. The cubic root of 21987648 is about 280.1514826575.

The spelling of 21987648 in words is "twenty-one million, nine hundred eighty-seven thousand, six hundred forty-eight".