21382645 has 4 divisors (see below), whose sum is σ = 25659180. Its totient is φ = 17106112.

The previous prime is 21382597. The next prime is 21382661. The reversal of 21382645 is 54628312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5716881 + 15665764 = 2391^2 + 3958^2 .

It is a cyclic number.

It is not a de Polignac number, because 21382645 - 2¹³ = 21374453 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 3 ways as a sum of consecutive naturals, for example, 2138260 + ... + 2138269.

It is an arithmetic number, because the mean of its divisors is an integer number (6414795).

Almost surely, 2^21382645 is an apocalyptic number.

It is an amenable number.

21382645 is a deficient number, since it is larger than the sum of its proper divisors (4276535).

21382645 is an equidigital number, since it uses as much as digits as its factorization.

21382645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4276534.

The product of its digits is 11520, while the sum is 31.

The square root of 21382645 is about 4624.1372168222. The cubic root of 21382645 is about 277.5580378027.

The spelling of 21382645 in words is "twenty-one million, three hundred eighty-two thousand, six hundred forty-five".