21111031061 has 2 divisors, whose sum is σ = 21111031062. Its totient is φ = 21111031060.

The previous prime is 21111031049. The next prime is 21111031087. The reversal of 21111031061 is 16013011112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17590982161 + 3520048900 = 132631^2 + 59330^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21111031061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21111031021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555515530 + 10555515531.

It is an arithmetic number, because the mean of its divisors is an integer number (10555515531).

Almost surely, 2^21111031061 is an apocalyptic number.

It is an amenable number.

21111031061 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111031061 is an equidigital number, since it uses as much as digits as its factorization.

21111031061 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 17.

Adding to 21111031061 its reverse (16013011112), we get a palindrome (37124042173).

The spelling of 21111031061 in words is "twenty-one billion, one hundred eleven million, thirty-one thousand, sixty-one".