21005320053 has 4 divisors (see below), whose sum is σ = 28007093408. Its totient is φ = 14003546700.

The previous prime is 21005320043. The next prime is 21005320081. The reversal of 21005320053 is 35002350012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21005320053 - 2⁶ = 21005319989 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 (21005320043) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3500886673 + ... + 3500886678.

It is an arithmetic number, because the mean of its divisors is an integer number (7001773352).

Almost surely, 2^21005320053 is an apocalyptic number.

It is an amenable number.

21005320053 is a deficient number, since it is larger than the sum of its proper divisors (7001773355).

21005320053 is an equidigital number, since it uses as much as digits as its factorization.

21005320053 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7001773354.

The product of its (nonzero) digits is 900, while the sum is 21.

Adding to 21005320053 its reverse (35002350012), we get a palindrome (56007670065).

The spelling of 21005320053 in words is "twenty-one billion, five million, three hundred twenty thousand, fifty-three".