21023648 has 12 divisors (see below), whose sum is σ = 41390370. Its totient is φ = 10511808.

The previous prime is 21023641. The next prime is 21023663. The reversal of 21023648 is 84632012.

It can be written as a sum of positive squares in only one way, i.e., 14531344 + 6492304 = 3812^2 + 2548^2 .

It is not an unprimeable number, because it can be changed into a prime (21023641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328463 + ... + 328526.

Almost surely, 2^21023648 is an apocalyptic number.

It is an amenable number.

21023648 is a deficient number, since it is larger than the sum of its proper divisors (20366722).

21023648 is an equidigital number, since it uses as much as digits as its factorization.

21023648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 656999 (or 656991 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 26.

The square root of 21023648 is about 4585.1551773086. The cubic root of 21023648 is about 275.9959391687.

The spelling of 21023648 in words is "twenty-one million, twenty-three thousand, six hundred forty-eight".