21005383 has 8 divisors (see below), whose sum is σ = 24780800. Its totient is φ = 17423640.

The previous prime is 21005363. The next prime is 21005399. The reversal of 21005383 is 38350012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21005383 is a prime.

It is a super-2 number, since 2×21005383² = 882452229953378, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21005363) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 48183 + ... + 48616.

It is an arithmetic number, because the mean of its divisors is an integer number (3097600).

Almost surely, 2^21005383 is an apocalyptic number.

21005383 is a deficient number, since it is larger than the sum of its proper divisors (3775417).

21005383 is an equidigital number, since it uses as much as digits as its factorization.

21005383 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 96837.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21005383 is about 4583.1629907739. The cubic root of 21005383 is about 275.9159890985.

Adding to 21005383 its reverse (38350012), we get a palindrome (59355395).

The spelling of 21005383 in words is "twenty-one million, five thousand, three hundred eighty-three".