21500443045021 has 16 divisors (see below), whose sum is σ = 21788884880640. Its totient is φ = 21212412549120.

The previous prime is 21500443044989. The next prime is 21500443045043. The reversal of 21500443045021 is 12054034400512.

It is a cyclic number.

It is not a de Polignac number, because 21500443045021 - 2⁵ = 21500443044989 is a prime.

It is a super-2 number, since 2×21500443045021² (a number of 27 digits) 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 (21500443045061) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1553381061 + ... + 1553394901.

It is an arithmetic number, because the mean of its divisors is an integer number (1361805305040).

Almost surely, 2^{21500443045021} is an apocalyptic number.

It is an amenable number.

21500443045021 is a deficient number, since it is larger than the sum of its proper divisors (288441835619).

21500443045021 is a wasteful number, since it uses less digits than its factorization.

21500443045021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27204.

The product of its (nonzero) digits is 19200, while the sum is 31.

Adding to 21500443045021 its reverse (12054034400512), we get a palindrome (33554477445533).

The spelling of 21500443045021 in words is "twenty-one trillion, five hundred billion, four hundred forty-three million, forty-five thousand, twenty-one".