1221000 has 128 divisors (see below), whose sum is σ = 4268160. Its totient is φ = 288000.

The previous prime is 1220993. The next prime is 1221019. The reversal of 1221000 is 1221.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (6).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is a self number, because there is not a number n which added to its sum of digits gives 1221000.

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 31 ways as a sum of consecutive naturals, for example, 32982 + ... + 33018.

It is an arithmetic number, because the mean of its divisors is an integer number (33345).

2^1221000 is an apocalyptic number.

1221000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2134080).

1221000 is an abundant number, since it is smaller than the sum of its proper divisors (3047160).

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

1221000 is a wasteful number, since it uses less digits than its factorization.

1221000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72 (or 58 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 6.

The square root of 1221000 is about 1104.9886877249. The cubic root of 1221000 is about 106.8821598432.

Adding to 1221000 its reverse (1221), we get a palindrome (1222221).

1221000 divided by its reverse (1221) gives a cube (1000 = 10³).

It can be divided in two parts, 12 and 21000, that added together give a palindrome (21012).

The spelling of 1221000 in words is "one million, two hundred twenty-one thousand".