1221280 has 48 divisors (see below), whose sum is σ = 3061800. Its totient is φ = 458752.

The previous prime is 1221251. The next prime is 1221289. The reversal of 1221280 is 821221.

It can be written as a sum of positive squares in 4 ways, for example, as 1140624 + 80656 = 1068^2 + 284^2 .

It is a Harshad number since it is a multiple of its sum of digits (16).

It is not an unprimeable number, because it can be changed into a prime (1221289) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 2496 + ... + 2944.

2^1221280 is an apocalyptic number.

1221280 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 1221280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1530900).

1221280 is an abundant number, since it is smaller than the sum of its proper divisors (1840520).

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

1221280 is a wasteful number, since it uses less digits than its factorization.

1221280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 481 (or 473 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 16.

The square root of 1221280 is about 1105.1153785918. The cubic root of 1221280 is about 106.8903292992.

The spelling of 1221280 in words is "one million, two hundred twenty-one thousand, two hundred eighty".