1131551221 has 4 divisors (see below), whose sum is σ = 1132739532. Its totient is φ = 1130362912.

The previous prime is 1131551191. The next prime is 1131551227. The reversal of 1131551221 is 1221551311.

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

It can be written as a sum of positive squares in 2 ways, for example, as 552908196 + 578643025 = 23514^2 + 24055^2 .

It is a cyclic number.

It is not a de Polignac number, because 1131551221 - 2¹⁷ = 1131420149 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1131551192 and 1131551201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1131551227) 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, 592726 + ... + 594631.

It is an arithmetic number, because the mean of its divisors is an integer number (283184883).

Almost surely, 2^1131551221 is an apocalyptic number.

It is an amenable number.

1131551221 is a deficient number, since it is larger than the sum of its proper divisors (1188311).

1131551221 is an equidigital number, since it uses as much as digits as its factorization.

1131551221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1188310.

The product of its digits is 300, while the sum is 22.

The square root of 1131551221 is about 33638.5377357578. The cubic root of 1131551221 is about 1042.0568333765.

The spelling of 1131551221 in words is "one billion, one hundred thirty-one million, five hundred fifty-one thousand, two hundred twenty-one".