21087648 has 48 divisors (see below), whose sum is σ = 61508160. Its totient is φ = 7028928.

The previous prime is 21087643. The next prime is 21087683. The reversal of 21087648 is 84678012.

21087648 is a `hidden beast` number, since 2 + 1 + 0 + 8 + 7 + 648 = 666.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (21087641) 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, 11340 + ... + 13067.

It is an arithmetic number, because the mean of its divisors is an integer number (1281420).

Almost surely, 2^21087648 is an apocalyptic number.

It is an amenable number.

21087648 is an abundant number, since it is smaller than the sum of its proper divisors (40420512).

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

21087648 is a wasteful number, since it uses less digits than its factorization.

21087648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24426 (or 24412 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 21087648 is about 4592.1289180510. The cubic root of 21087648 is about 276.2757169127.

The spelling of 21087648 in words is "twenty-one million, eighty-seven thousand, six hundred forty-eight".