21648999 has 16 divisors (see below), whose sum is σ = 31034880. Its totient is φ = 13380480.

The previous prime is 21648997. The next prime is 21649031. The reversal of 21648999 is 99984612.

It is not a de Polignac number, because 21648999 - 2¹ = 21648997 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21648997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1362 + ... + 6719.

It is an arithmetic number, because the mean of its divisors is an integer number (1939680).

Almost surely, 2^21648999 is an apocalyptic number.

21648999 is a deficient number, since it is larger than the sum of its proper divisors (9385881).

21648999 is a wasteful number, since it uses less digits than its factorization.

21648999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8150.

The product of its digits is 279936, while the sum is 48.

The square root of 21648999 is about 4652.8484823815. The cubic root of 21648999 is about 278.7057572875.

The spelling of 21648999 in words is "twenty-one million, six hundred forty-eight thousand, nine hundred ninety-nine".