1221603840 has 240 divisors, whose sum is σ = 4348134648. Its totient is φ = 316735488.

The previous prime is 1221603839. The next prime is 1221603847. The reversal of 1221603840 is 483061221.

1221603840 is a `hidden beast` number, since 1 + 221 + 60 + 384 + 0 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1217730816 + 3873024 = 34896^2 + 1968^2 .

It is a tau number, because it is divible by the number of its divisors (240).

It is not an unprimeable number, because it can be changed into a prime (1221603847) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 851764 + ... + 853196.

Almost surely, 2^1221603840 is an apocalyptic number.

1221603840 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 1221603840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2174067324).

1221603840 is an abundant number, since it is smaller than the sum of its proper divisors (3126530808).

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

1221603840 is a wasteful number, since it uses less digits than its factorization.

1221603840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1499 (or 1480 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 1221603840 is about 34951.4497553392. The cubic root of 1221603840 is about 1068.9977630155.

The spelling of 1221603840 in words is "one billion, two hundred twenty-one million, six hundred three thousand, eight hundred forty".