211109981 has 2 divisors, whose sum is σ = 211109982. Its totient is φ = 211109980.

The previous prime is 211109957. The next prime is 211109989. The reversal of 211109981 is 189901112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 163968025 + 47141956 = 12805^2 + 6866^2 .

It is a cyclic number.

It is not a de Polignac number, because 211109981 - 2⁶ = 211109917 is a prime.

It is a super-2 number, since 2×211109981² = 89134848155640722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (211109989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105554990 + 105554991.

It is an arithmetic number, because the mean of its divisors is an integer number (105554991).

Almost surely, 2^211109981 is an apocalyptic number.

It is an amenable number.

211109981 is a deficient number, since it is larger than the sum of its proper divisors (1).

211109981 is an equidigital number, since it uses as much as digits as its factorization.

211109981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 32.

The square root of 211109981 is about 14529.6242552930. The cubic root of 211109981 is about 595.4376000751.

The spelling of 211109981 in words is "two hundred eleven million, one hundred nine thousand, nine hundred eighty-one".