21121111202161 has 2 divisors, whose sum is σ = 21121111202162. Its totient is φ = 21121111202160.

The previous prime is 21121111202099. The next prime is 21121111202189. The reversal of 21121111202161 is 16120211112112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20138831992161 + 982279210000 = 4487631^2 + 991100^2 .

It is a cyclic number.

It is not a de Polignac number, because 21121111202161 - 2¹⁵ = 21121111169393 is a prime.

It is a super-2 number, since 2×21121111202161² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21121111202461) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560555601080 + 10560555601081.

It is an arithmetic number, because the mean of its divisors is an integer number (10560555601081).

Almost surely, 2^{21121111202161} is an apocalyptic number.

It is an amenable number.

21121111202161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121111202161 is an equidigital number, since it uses as much as digits as its factorization.

21121111202161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96, while the sum is 22.

Adding to 21121111202161 its reverse (16120211112112), we get a palindrome (37241322314273).

The spelling of 21121111202161 in words is "twenty-one trillion, one hundred twenty-one billion, one hundred eleven million, two hundred two thousand, one hundred sixty-one".