21051648 has 54 divisors (see below), whose sum is σ = 60703734. Its totient is φ = 7016448.

The previous prime is 21051643. The next prime is 21051673. The reversal of 21051648 is 84615012.

21051648 is a `hidden beast` number, since 2 + 10 + 5 + 1 + 648 = 666.

It can be written as a sum of positive squares in only one way, i.e., 11614464 + 9437184 = 3408^2 + 3072^2 .

It is not an unprimeable number, because it can be changed into a prime (21051643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2265 + ... + 6872.

Almost surely, 2^21051648 is an apocalyptic number.

It is an amenable number.

21051648 is an abundant number, since it is smaller than the sum of its proper divisors (39652086).

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

21051648 is an equidigital number, since it uses as much as digits as its factorization.

21051648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9159 (or 9142 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21051648 is about 4588.2074931284. The cubic root of 21051648 is about 276.1184116987.

The spelling of 21051648 in words is "twenty-one million, fifty-one thousand, six hundred forty-eight".