1155221 has 4 divisors (see below), whose sum is σ = 1205472. Its totient is φ = 1104972.

The previous prime is 1155211. The next prime is 1155223. The reversal of 1155221 is 1225511.

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.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1155221 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1155221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1155223) 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, 25091 + ... + 25136.

It is an arithmetic number, because the mean of its divisors is an integer number (301368).

2^1155221 is an apocalyptic number.

It is an amenable number.

1155221 is a deficient number, since it is larger than the sum of its proper divisors (50251).

1155221 is an equidigital number, since it uses as much as digits as its factorization.

1155221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50250.

The product of its digits is 100, while the sum is 17.

The square root of 1155221 is about 1074.8120765976. The cubic root of 1155221 is about 104.9272663334.

It can be divided in two parts, 1155 and 221, that multiplied together give a triangular number (255255 = T₇₁₄).

The spelling of 1155221 in words is "one million, one hundred fifty-five thousand, two hundred twenty-one".