1221440 has 56 divisors (see below), whose sum is σ = 3182112. Its totient is φ = 442880.

The previous prime is 1221427. The next prime is 1221443. The reversal of 1221440 is 441221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221443) 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, 3347 + ... + 3693.

2^1221440 is an apocalyptic number.

1221440 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 1221440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1591056).

1221440 is an abundant number, since it is smaller than the sum of its proper divisors (1960672).

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

1221440 is a wasteful number, since it uses less digits than its factorization.

1221440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 375 (or 365 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 14.

The square root of 1221440 is about 1105.1877668523. The cubic root of 1221440 is about 106.8949969992.

Adding to 1221440 its reverse (441221), we get a palindrome (1662661).

It can be divided in two parts, 1221 and 440, that added together give a palindrome (1661).

The spelling of 1221440 in words is "one million, two hundred twenty-one thousand, four hundred forty".