1155561321 has 4 divisors (see below), whose sum is σ = 1540748432. Its totient is φ = 770374212.

The previous prime is 1155561313. The next prime is 1155561353. The reversal of 1155561321 is 1231655511.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1231655511 = 3 ⋅410551837.

It is not a de Polignac number, because 1155561321 - 2³ = 1155561313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1155561371) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 192593551 + ... + 192593556.

It is an arithmetic number, because the mean of its divisors is an integer number (385187108).

Almost surely, 2^1155561321 is an apocalyptic number.

It is an amenable number.

1155561321 is a deficient number, since it is larger than the sum of its proper divisors (385187111).

1155561321 is an equidigital number, since it uses as much as digits as its factorization.

1155561321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 385187110.

The product of its digits is 4500, while the sum is 30.

The square root of 1155561321 is about 33993.5482260973. The cubic root of 1155561321 is about 1049.3756896413.

The spelling of 1155561321 in words is "one billion, one hundred fifty-five million, five hundred sixty-one thousand, three hundred twenty-one".