21011011101221 has 2 divisors, whose sum is σ = 21011011101222. Its totient is φ = 21011011101220.

The previous prime is 21011011101161. The next prime is 21011011101251. The reversal of 21011011101221 is 12210111011012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21007097222500 + 3913878721 = 4583350^2 + 62561^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011011101221 - 2²² = 21011006906917 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21011011101196 and 21011011101205.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21011011101251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505505550610 + 10505505550611.

It is an arithmetic number, because the mean of its divisors is an integer number (10505505550611).

Almost surely, 2^{21011011101221} is an apocalyptic number.

It is an amenable number.

21011011101221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011011101221 is an equidigital number, since it uses as much as digits as its factorization.

21011011101221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8, while the sum is 14.

Adding to 21011011101221 its reverse (12210111011012), we get a palindrome (33221122112233).

The spelling of 21011011101221 in words is "twenty-one trillion, eleven billion, eleven million, one hundred one thousand, two hundred twenty-one".