21051545200021 has 64 divisors (see below), whose sum is σ = 26306941248000. Its totient is φ = 16787815833600.

The previous prime is 21051545200009. The next prime is 21051545200027. The reversal of 21051545200021 is 12000254515012.

It is not a de Polignac number, because 21051545200021 - 2⁵ = 21051545199989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21051545200027) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 254779911 + ... + 254862523.

It is an arithmetic number, because the mean of its divisors is an integer number (411045957000).

Almost surely, 2^{21051545200021} is an apocalyptic number.

It is an amenable number.

21051545200021 is a deficient number, since it is larger than the sum of its proper divisors (5255396047979).

21051545200021 is an equidigital number, since it uses as much as digits as its factorization.

21051545200021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83355 (or 83341 counting only the distinct ones).

The product of its (nonzero) digits is 4000, while the sum is 28.

Adding to 21051545200021 its reverse (12000254515012), we get a palindrome (33051799715033).

The spelling of 21051545200021 in words is "twenty-one trillion, fifty-one billion, five hundred forty-five million, two hundred thousand, twenty-one".