1221220 has 96 divisors (see below), whose sum is σ = 3499776. Its totient is φ = 345600.

The previous prime is 1221197. The next prime is 1221221. The reversal of 1221220 is 221221.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 1221197 and 1221206.

It is not an unprimeable number, because it can be changed into a prime (1221221) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19990 + ... + 20050.

It is an arithmetic number, because the mean of its divisors is an integer number (36456).

2^1221220 is an apocalyptic number.

1221220 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 1221220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1749888).

1221220 is an abundant number, since it is smaller than the sum of its proper divisors (2278556).

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

1221220 is a wasteful number, since it uses less digits than its factorization.

1221220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101 (or 99 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 1221220 is about 1105.0882317716. The cubic root of 1221220 is about 106.8885788066. Note that the first 3 decimals are identical.

Adding to 1221220 its reverse (221221), we get a palindrome (1442441).

Subtracting from 1221220 its reverse (221221), we obtain a palindrome (999999).

It can be divided in two parts, 1221 and 220, that added together give a palindrome (1441).

The spelling of 1221220 in words is "one million, two hundred twenty-one thousand, two hundred twenty".