21645983 has 8 divisors (see below), whose sum is σ = 22160160. Its totient is φ = 21137760.

The previous prime is 21645937. The next prime is 21646003. The reversal of 21645983 is 38954612.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21645983 - 2¹² = 21641887 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21645683) 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 7 ways as a sum of consecutive naturals, for example, 6341 + ... + 9137.

It is an arithmetic number, because the mean of its divisors is an integer number (2770020).

Almost surely, 2^21645983 is an apocalyptic number.

21645983 is a deficient number, since it is larger than the sum of its proper divisors (514177).

21645983 is a wasteful number, since it uses less digits than its factorization.

21645983 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2977.

The product of its digits is 51840, while the sum is 38.

The square root of 21645983 is about 4652.5243685552. The cubic root of 21645983 is about 278.6928141855.

The spelling of 21645983 in words is "twenty-one million, six hundred forty-five thousand, nine hundred eighty-three".