21111021181 has 2 divisors, whose sum is σ = 21111021182. Its totient is φ = 21111021180.

The previous prime is 21111021133. The next prime is 21111021203. The reversal of 21111021181 is 18112011112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18693725625 + 2417295556 = 136725^2 + 49166^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111021181 - 2³¹ = 18963537533 is a prime.

It is a super-2 number, since 2×21111021181² (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 (21111021101) 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, 10555510590 + 10555510591.

It is an arithmetic number, because the mean of its divisors is an integer number (10555510591).

Almost surely, 2^21111021181 is an apocalyptic number.

It is an amenable number.

21111021181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111021181 is an equidigital number, since it uses as much as digits as its factorization.

21111021181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32, while the sum is 19.

Adding to 21111021181 its reverse (18112011112), we get a palindrome (39223032293).

The spelling of 21111021181 in words is "twenty-one billion, one hundred eleven million, twenty-one thousand, one hundred eighty-one".