21202121111 has 2 divisors, whose sum is σ = 21202121112. Its totient is φ = 21202121110.

The previous prime is 21202121077. The next prime is 21202121173. The reversal of 21202121111 is 11112120212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21202121111 - 2¹⁸ = 21201858967 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21202121191) 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, 10601060555 + 10601060556.

It is an arithmetic number, because the mean of its divisors is an integer number (10601060556).

Almost surely, 2^21202121111 is an apocalyptic number.

21202121111 is a deficient number, since it is larger than the sum of its proper divisors (1).

21202121111 is an equidigital number, since it uses as much as digits as its factorization.

21202121111 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21202121111 its reverse (11112120212), we get a palindrome (32314241323).

It can be divided in two parts, 2120212 and 1111, that multiplied together give a palindrome (2355555532).

The spelling of 21202121111 in words is "twenty-one billion, two hundred two million, one hundred twenty-one thousand, one hundred eleven".