1221100 has 18 divisors (see below), whose sum is σ = 2650004. Its totient is φ = 488400.

The previous prime is 1221097. The next prime is 1221113. The reversal of 1221100 is 11221.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6006 + ... + 6205.

2^1221100 is an apocalyptic number.

1221100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1221100 is an abundant number, since it is smaller than the sum of its proper divisors (1428904).

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

1221100 is a wasteful number, since it uses less digits than its factorization.

1221100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12225 (or 12218 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 7.

The square root of 1221100 is about 1105.0339361305. The cubic root of 1221100 is about 106.8850776494.

Adding to 1221100 its reverse (11221), we get a palindrome (1232321).

It can be divided in two parts, 12 and 21100, that added together give a palindrome (21112).

The spelling of 1221100 in words is "one million, two hundred twenty-one thousand, one hundred".