1221155 has 8 divisors (see below), whose sum is σ = 1578192. Its totient is φ = 901728.

The previous prime is 1221131. The next prime is 1221163. The reversal of 1221155 is 5511221.

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 1221155 - 2¹⁶ = 1155619 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9329 + ... + 9458.

It is an arithmetic number, because the mean of its divisors is an integer number (197274).

2^1221155 is an apocalyptic number.

1221155 is a deficient number, since it is larger than the sum of its proper divisors (357037).

1221155 is a wasteful number, since it uses less digits than its factorization.

1221155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18805.

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

The square root of 1221155 is about 1105.0588219638. The cubic root of 1221155 is about 106.8866823749.

Adding to 1221155 its reverse (5511221), we get a palindrome (6732376).

The spelling of 1221155 in words is "one million, two hundred twenty-one thousand, one hundred fifty-five".