1161556221 has 12 divisors (see below), whose sum is σ = 1801597632. Its totient is φ = 663746328.

The previous prime is 1161556213. The next prime is 1161556259. The reversal of 1161556221 is 1226551611.

It is not a de Polignac number, because 1161556221 - 2³ = 1161556213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1161556021) 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 11 ways as a sum of consecutive naturals, for example, 3950725 + ... + 3951018.

It is an arithmetic number, because the mean of its divisors is an integer number (150133136).

Almost surely, 2^1161556221 is an apocalyptic number.

It is an amenable number.

1161556221 is a deficient number, since it is larger than the sum of its proper divisors (640041411).

1161556221 is an equidigital number, since it uses as much as digits as its factorization.

1161556221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7901760 (or 7901753 counting only the distinct ones).

The product of its digits is 3600, while the sum is 30.

The square root of 1161556221 is about 34081.6111855059. The cubic root of 1161556221 is about 1051.1872348655.

The spelling of 1161556221 in words is "one billion, one hundred sixty-one million, five hundred fifty-six thousand, two hundred twenty-one".