21987248 has 20 divisors (see below), whose sum is σ = 42679560. Its totient is φ = 10973184.

The previous prime is 21987247. The next prime is 21987257. The reversal of 21987248 is 84278912.

It is a super-2 number, since 2×21987248² = 966878149227008, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21987247) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11411 + ... + 13197.

It is an arithmetic number, because the mean of its divisors is an integer number (2133978).

Almost surely, 2^21987248 is an apocalyptic number.

It is an amenable number.

21987248 is a deficient number, since it is larger than the sum of its proper divisors (20692312).

21987248 is a wasteful number, since it uses less digits than its factorization.

21987248 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2564 (or 2558 counting only the distinct ones).

The product of its digits is 64512, while the sum is 41.

The square root of 21987248 is about 4689.0561950141. The cubic root of 21987248 is about 280.1497838056.

The spelling of 21987248 in words is "twenty-one million, nine hundred eighty-seven thousand, two hundred forty-eight".