21111000181 has 2 divisors, whose sum is σ = 21111000182. Its totient is φ = 21111000180.

The previous prime is 21111000173. The next prime is 21111000191. The reversal of 21111000181 is 18100011112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14575732900 + 6535267281 = 120730^2 + 80841^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111000181 - 2³ = 21111000173 is a prime.

It is a super-2 number, since 2×21111000181² (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 (21111000191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555500090 + 10555500091.

It is an arithmetic number, because the mean of its divisors is an integer number (10555500091).

Almost surely, 2^21111000181 is an apocalyptic number.

It is an amenable number.

21111000181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111000181 is an equidigital number, since it uses as much as digits as its factorization.

21111000181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 16.

Adding to 21111000181 its reverse (18100011112), we get a palindrome (39211011293).

The spelling of 21111000181 in words is "twenty-one billion, one hundred eleven million, one hundred eighty-one", and thus it is an aban number.