211561121 has 2 divisors, whose sum is σ = 211561122. Its totient is φ = 211561120.

The previous prime is 211561109. The next prime is 211561139. The reversal of 211561121 is 121165112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 211557025 + 4096 = 14545^2 + 64^2 .

It is a cyclic number.

It is not a de Polignac number, because 211561121 - 2¹⁴ = 211544737 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 211561093 and 211561102.

It is not a weakly prime, because it can be changed into another prime (211561321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105780560 + 105780561.

It is an arithmetic number, because the mean of its divisors is an integer number (105780561).

Almost surely, 2^211561121 is an apocalyptic number.

It is an amenable number.

211561121 is a deficient number, since it is larger than the sum of its proper divisors (1).

211561121 is an equidigital number, since it uses as much as digits as its factorization.

211561121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 120, while the sum is 20.

The square root of 211561121 is about 14545.1408037186. The cubic root of 211561121 is about 595.8614464422.

It can be divided in two parts, 2115 and 61121, that added together give a palindrome (63236).

The spelling of 211561121 in words is "two hundred eleven million, five hundred sixty-one thousand, one hundred twenty-one".