1221156 has 30 divisors (see below), whose sum is σ = 3193190. Its totient is φ = 406944.

The previous prime is 1221131. The next prime is 1221163. The reversal of 1221156 is 6511221.

It can be written as a sum of positive squares in only one way, i.e., 1166400 + 54756 = 1080^2 + 234^2 .

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1561 + ... + 2208.

2^1221156 is an apocalyptic number.

It is an amenable number.

1221156 is an abundant number, since it is smaller than the sum of its proper divisors (1972034).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1221156 is a wasteful number, since it uses less digits than its factorization.

1221156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3785 (or 3774 counting only the distinct ones).

The product of its digits is 120, while the sum is 18.

The square root of 1221156 is about 1105.0592744283. The cubic root of 1221156 is about 106.8867115513.

Adding to 1221156 its reverse (6511221), we get a palindrome (7732377).

The spelling of 1221156 in words is "one million, two hundred twenty-one thousand, one hundred fifty-six".