1221043320 has 192 divisors, whose sum is σ = 4732715520. Its totient is φ = 266948352.

The previous prime is 1221043319. The next prime is 1221043321. The reversal of 1221043320 is 233401221.

1221043320 is a `hidden beast` number, since 1 + 2 + 210 + 433 + 20 = 666.

It is an interprime number because it is at equal distance from previous prime (1221043319) and next prime (1221043321).

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

It is a junction number, because it is equal to n+sod(n) for n = 1221043293 and 1221043302.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221043321) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 47427 + ... + 68493.

It is an arithmetic number, because the mean of its divisors is an integer number (24649560).

Almost surely, 2^1221043320 is an apocalyptic number.

1221043320 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 1221043320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2366357760).

1221043320 is an abundant number, since it is smaller than the sum of its proper divisors (3511672200).

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

1221043320 is a wasteful number, since it uses less digits than its factorization.

1221043320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21114 (or 21107 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 1221043320 is about 34943.4302838173. The cubic root of 1221043320 is about 1068.8342385638.

Adding to 1221043320 its reverse (233401221), we get a palindrome (1454444541).

The spelling of 1221043320 in words is "one billion, two hundred twenty-one million, forty-three thousand, three hundred twenty".