1155531221 has 8 divisors (see below), whose sum is σ = 1257248664. Its totient is φ = 1055646720.

The previous prime is 1155531211. The next prime is 1155531239. The reversal of 1155531221 is 1221355511.

It can be written as a sum of positive squares in 4 ways, for example, as 154504900 + 1001026321 = 12430^2 + 31639^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1155531221 - 2¹⁰ = 1155530197 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1155531211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 456920 + ... + 459441.

It is an arithmetic number, because the mean of its divisors is an integer number (157156083).

Almost surely, 2^1155531221 is an apocalyptic number.

It is an amenable number.

1155531221 is a deficient number, since it is larger than the sum of its proper divisors (101717443).

1155531221 is an equidigital number, since it uses as much as digits as its factorization.

1155531221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 916471.

The product of its digits is 1500, while the sum is 26.

The square root of 1155531221 is about 33993.1054921436. The cubic root of 1155531221 is about 1049.3665782014.

Adding to 1155531221 its reverse (1221355511), we get a palindrome (2376886732).

The spelling of 1155531221 in words is "one billion, one hundred fifty-five million, five hundred thirty-one thousand, two hundred twenty-one".