21011111101 has 2 divisors, whose sum is σ = 21011111102. Its totient is φ = 21011111100.

The previous prime is 21011111029. The next prime is 21011111119. The reversal of 21011111101 is 10111111012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11031300900 + 9979810201 = 105030^2 + 99899^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011111101 - 2⁷ = 21011110973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21011111131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505555550 + 10505555551.

It is an arithmetic number, because the mean of its divisors is an integer number (10505555551).

Almost surely, 2^21011111101 is an apocalyptic number.

It is an amenable number.

21011111101 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011111101 is an equidigital number, since it uses as much as digits as its factorization.

21011111101 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2, while the sum is 10.

Adding to 21011111101 its reverse (10111111012), we get a palindrome (31122222113).

It can be divided in two parts, 2 and 1011111101, that multiplied together give a palindrome (2022222202).

The spelling of 21011111101 in words is "twenty-one billion, eleven million, one hundred eleven thousand, one hundred one".