21318053 has 4 divisors (see below), whose sum is σ = 21350220. Its totient is φ = 21285888.

The previous prime is 21318047. The next prime is 21318091. The reversal of 21318053 is 35081312.

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 18335524 + 2982529 = 4282^2 + 1727^2 .

It is a cyclic number.

It is not a de Polignac number, because 21318053 - 2¹⁰ = 21317029 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 (21318653) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15068 + ... + 16421.

It is an arithmetic number, because the mean of its divisors is an integer number (5337555).

Almost surely, 2^21318053 is an apocalyptic number.

It is an amenable number.

21318053 is a deficient number, since it is larger than the sum of its proper divisors (32167).

21318053 is an equidigital number, since it uses as much as digits as its factorization.

21318053 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32166.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 21318053 is about 4617.1477126035. The cubic root of 21318053 is about 277.2782764780.

Adding to 21318053 its reverse (35081312), we get a palindrome (56399365).

The spelling of 21318053 in words is "twenty-one million, three hundred eighteen thousand, fifty-three".