21068645 has 16 divisors (see below), whose sum is σ = 28168560. Its totient is φ = 15020544.

The previous prime is 21068617. The next prime is 21068653. The reversal of 21068645 is 54686012.

It can be written as a sum of positive squares in 8 ways, for example, as 37249 + 21031396 = 193^2 + 4586^2 .

It is a cyclic number.

It is not a de Polignac number, because 21068645 - 2¹⁰ = 21067621 is a prime.

It is a congruent number.

It is an unprimeable number.

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, 3704 + ... + 7473.

It is an arithmetic number, because the mean of its divisors is an integer number (1760535).

Almost surely, 2^21068645 is an apocalyptic number.

It is an amenable number.

21068645 is a deficient number, since it is larger than the sum of its proper divisors (7099915).

21068645 is a wasteful number, since it uses less digits than its factorization.

21068645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11224.

The product of its (nonzero) digits is 11520, while the sum is 32.

The square root of 21068645 is about 4590.0593678078. The cubic root of 21068645 is about 276.1927039366.

The spelling of 21068645 in words is "twenty-one million, sixty-eight thousand, six hundred forty-five".