21201111109 has 2 divisors, whose sum is σ = 21201111110. Its totient is φ = 21201111108.

The previous prime is 21201111101. The next prime is 21201111131. The reversal of 21201111109 is 90111110212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11512646209 + 9688464900 = 107297^2 + 98430^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201111109 - 2³ = 21201111101 is a prime.

It is a super-2 number, since 2×21201111109² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21201111101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600555554 + 10600555555.

It is an arithmetic number, because the mean of its divisors is an integer number (10600555555).

Almost surely, 2^21201111109 is an apocalyptic number.

It is an amenable number.

21201111109 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201111109 is an equidigital number, since it uses as much as digits as its factorization.

21201111109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36, while the sum is 19.

The spelling of 21201111109 in words is "twenty-one billion, two hundred one million, one hundred eleven thousand, one hundred nine".