21220101212173 has 2 divisors, whose sum is σ = 21220101212174. Its totient is φ = 21220101212172.

The previous prime is 21220101212081. The next prime is 21220101212213. The reversal of 21220101212173 is 37121210102212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16177103393929 + 5042997818244 = 4022077^2 + 2245662^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21220101212173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21220101212273) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610050606086 + 10610050606087.

It is an arithmetic number, because the mean of its divisors is an integer number (10610050606087).

Almost surely, 2^{21220101212173} is an apocalyptic number.

It is an amenable number.

21220101212173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21220101212173 is an equidigital number, since it uses as much as digits as its factorization.

21220101212173 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 672, while the sum is 25.

Adding to 21220101212173 its reverse (37121210102212), we get a palindrome (58341311314385).

The spelling of 21220101212173 in words is "twenty-one trillion, two hundred twenty billion, one hundred one million, two hundred twelve thousand, one hundred seventy-three".