1155721211 has 4 divisors (see below), whose sum is σ = 1180311072. Its totient is φ = 1131131352.

The previous prime is 1155721187. The next prime is 1155721271. The reversal of 1155721211 is 1121275511.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1155721211 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1155721271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12294860 + ... + 12294953.

It is an arithmetic number, because the mean of its divisors is an integer number (295077768).

Almost surely, 2^1155721211 is an apocalyptic number.

1155721211 is a deficient number, since it is larger than the sum of its proper divisors (24589861).

1155721211 is an equidigital number, since it uses as much as digits as its factorization.

1155721211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24589860.

The product of its digits is 700, while the sum is 26.

The square root of 1155721211 is about 33995.8999145485. The cubic root of 1155721211 is about 1049.4240865944.

Adding to 1155721211 its reverse (1121275511), we get a palindrome (2276996722).

It can be divided in two parts, 11557 and 21211, that added together give a 15-th power (32768 = 2¹⁵).

The spelling of 1155721211 in words is "one billion, one hundred fifty-five million, seven hundred twenty-one thousand, two hundred eleven".