21221000222173 has 2 divisors, whose sum is σ = 21221000222174. Its totient is φ = 21221000222172.

The previous prime is 21221000222143. The next prime is 21221000222221. The reversal of 21221000222173 is 37122200012212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20273379744409 + 947620477764 = 4502597^2 + 973458^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221000222173 - 2²⁵ = 21220966667741 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221000222143) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610500111086 + 10610500111087.

It is an arithmetic number, because the mean of its divisors is an integer number (10610500111087).

Almost surely, 2^{21221000222173} is an apocalyptic number.

It is an amenable number.

21221000222173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221000222173 is an equidigital number, since it uses as much as digits as its factorization.

21221000222173 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1344, while the sum is 25.

Adding to 21221000222173 its reverse (37122200012212), we get a palindrome (58343200234385).

The spelling of 21221000222173 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred twenty-two thousand, one hundred seventy-three".