1221264 has 80 divisors (see below), whose sum is σ = 3839040. Its totient is φ = 368640.

The previous prime is 1221251. The next prime is 1221289. The reversal of 1221264 is 4621221.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nude number because it is divisible by every one of its digits.

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 15 ways as a sum of consecutive naturals, for example, 4624 + ... + 4880.

It is an arithmetic number, because the mean of its divisors is an integer number (47988).

2^1221264 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1221264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1919520).

1221264 is an abundant number, since it is smaller than the sum of its proper divisors (2617776).

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

1221264 is a wasteful number, since it uses less digits than its factorization.

1221264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 285 (or 273 counting only the distinct ones).

The product of its digits is 192, while the sum is 18.

The square root of 1221264 is about 1105.1081395049. The cubic root of 1221264 is about 106.8898625068.

Adding to 1221264 its reverse (4621221), we get a palindrome (5842485).

It can be divided in two parts, 1221 and 264, that added together give a triangular number (1485 = T₅₄).

The spelling of 1221264 in words is "one million, two hundred twenty-one thousand, two hundred sixty-four".