1221216 has 24 divisors (see below), whose sum is σ = 3205944. Its totient is φ = 407040.

The previous prime is 1221197. The next prime is 1221221. The reversal of 1221216 is 6121221.

It is a tau number, because it is divible by the number of its divisors (24).

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 1221195 and 1221204.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 6265 + ... + 6456.

It is an arithmetic number, because the mean of its divisors is an integer number (133581).

2^1221216 is an apocalyptic number.

1221216 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1221216 is an abundant number, since it is smaller than the sum of its proper divisors (1984728).

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

1221216 is a wasteful number, since it uses less digits than its factorization.

1221216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12734 (or 12726 counting only the distinct ones).

The product of its digits is 48, while the sum is 15.

The square root of 1221216 is about 1105.0864219598. The cubic root of 1221216 is about 106.8884621051. Note that the first 3 decimals are identical.

Adding to 1221216 its reverse (6121221), we get a palindrome (7342437).

The spelling of 1221216 in words is "one million, two hundred twenty-one thousand, two hundred sixteen".