11211210721 has 2 divisors, whose sum is σ = 11211210722. Its totient is φ = 11211210720.

The previous prime is 11211210719. The next prime is 11211210727. The reversal of 11211210721 is 12701211211.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11100729600 + 110481121 = 105360^2 + 10511^2 .

It is a cyclic number.

It is not a de Polignac number, because 11211210721 - 2¹ = 11211210719 is a prime.

Together with 11211210719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (11211210727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5605605360 + 5605605361.

It is an arithmetic number, because the mean of its divisors is an integer number (5605605361).

Almost surely, 2^11211210721 is an apocalyptic number.

It is an amenable number.

11211210721 is a deficient number, since it is larger than the sum of its proper divisors (1).

11211210721 is an equidigital number, since it uses as much as digits as its factorization.

11211210721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 56, while the sum is 19.

Adding to 11211210721 its reverse (12701211211), we get a palindrome (23912421932).

The spelling of 11211210721 in words is "eleven billion, two hundred eleven million, two hundred ten thousand, seven hundred twenty-one".