211009956721 has 2 divisors, whose sum is σ = 211009956722. Its totient is φ = 211009956720.

The previous prime is 211009956719. The next prime is 211009956733. The reversal of 211009956721 is 127659900112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 187467350625 + 23542606096 = 432975^2 + 153436^2 .

It is a cyclic number.

It is not a de Polignac number, because 211009956721 - 2¹ = 211009956719 is a prime.

Together with 211009956719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (211009956791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 105504978360 + 105504978361.

It is an arithmetic number, because the mean of its divisors is an integer number (105504978361).

Almost surely, 2^211009956721 is an apocalyptic number.

It is an amenable number.

211009956721 is a deficient number, since it is larger than the sum of its proper divisors (1).

211009956721 is an equidigital number, since it uses as much as digits as its factorization.

211009956721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 68040, while the sum is 43.

The spelling of 211009956721 in words is "two hundred eleven billion, nine million, nine hundred fifty-six thousand, seven hundred twenty-one".