21221111173 has 2 divisors, whose sum is σ = 21221111174. Its totient is φ = 21221111172.

The previous prime is 21221111167. The next prime is 21221111273. The reversal of 21221111173 is 37111112212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14370734884 + 6850376289 = 119878^2 + 82767^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221111173 - 2¹⁷ = 21220980101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221111113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610555586 + 10610555587.

It is an arithmetic number, because the mean of its divisors is an integer number (10610555587).

Almost surely, 2^21221111173 is an apocalyptic number.

It is an amenable number.

21221111173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221111173 is an equidigital number, since it uses as much as digits as its factorization.

21221111173 is an evil number, because the sum of its binary digits is even.

The product of its digits is 168, while the sum is 22.

Adding to 21221111173 its reverse (37111112212), we get a palindrome (58332223385).

The spelling of 21221111173 in words is "twenty-one billion, two hundred twenty-one million, one hundred eleven thousand, one hundred seventy-three".