21221020200173 has 2 divisors, whose sum is σ = 21221020200174. Its totient is φ = 21221020200172.

The previous prime is 21221020200157. The next prime is 21221020200223. The reversal of 21221020200173 is 37100202012212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20817118006084 + 403902194089 = 4562578^2 + 635533^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221020200173 - 2⁴ = 21221020200157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221020200773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610510100086 + 10610510100087.

It is an arithmetic number, because the mean of its divisors is an integer number (10610510100087).

Almost surely, 2^{21221020200173} is an apocalyptic number.

It is an amenable number.

21221020200173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221020200173 is an equidigital number, since it uses as much as digits as its factorization.

21221020200173 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 672, while the sum is 23.

Adding to 21221020200173 its reverse (37100202012212), we get a palindrome (58321222212385).

The spelling of 21221020200173 in words is "twenty-one trillion, two hundred twenty-one billion, twenty million, two hundred thousand, one hundred seventy-three".