21011211121211 has 2 divisors, whose sum is σ = 21011211121212. Its totient is φ = 21011211121210.

The previous prime is 21011211121207. The next prime is 21011211121231. The reversal of 21011211121211 is 11212111211012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21011211121211 - 2² = 21011211121207 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21011211121211.

It is not a weakly prime, because it can be changed into another prime (21011211121231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505605560605 + 10505605560606.

It is an arithmetic number, because the mean of its divisors is an integer number (10505605560606).

Almost surely, 2^{21011211121211} is an apocalyptic number.

21011211121211 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011211121211 is an equidigital number, since it uses as much as digits as its factorization.

21011211121211 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 17.

Adding to 21011211121211 its reverse (11212111211012), we get a palindrome (32223322332223).

The spelling of 21011211121211 in words is "twenty-one trillion, eleven billion, two hundred eleven million, one hundred twenty-one thousand, two hundred eleven".