21202121173 has 2 divisors, whose sum is σ = 21202121174. Its totient is φ = 21202121172.

The previous prime is 21202121111. The next prime is 21202121189. The reversal of 21202121173 is 37112120212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19221604164 + 1980517009 = 138642^2 + 44503^2 .

It is a cyclic number.

It is not a de Polignac number, because 21202121173 - 2¹⁷ = 21201990101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21202121273) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601060586 + 10601060587.

It is an arithmetic number, because the mean of its divisors is an integer number (10601060587).

Almost surely, 2^21202121173 is an apocalyptic number.

It is an amenable number.

21202121173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21202121173 is an equidigital number, since it uses as much as digits as its factorization.

21202121173 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 336, while the sum is 22.

Adding to 21202121173 its reverse (37112120212), we get a palindrome (58314241385).

The spelling of 21202121173 in words is "twenty-one billion, two hundred two million, one hundred twenty-one thousand, one hundred seventy-three".