1220643840 has 176 divisors, whose sum is σ = 4205160288. Its totient is φ = 300417024.

The previous prime is 1220643793. The next prime is 1220643869. The reversal of 1220643840 is 483460221.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 1220643798 and 1220643807.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 196624 + ... + 202736.

Almost surely, 2^1220643840 is an apocalyptic number.

1220643840 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 1220643840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2102580144).

1220643840 is an abundant number, since it is smaller than the sum of its proper divisors (2984516448).

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

1220643840 is a wasteful number, since it uses less digits than its factorization.

1220643840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6154 (or 6136 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 30.

The square root of 1220643840 is about 34937.7137202765. The cubic root of 1220643840 is about 1068.7176649018.

The spelling of 1220643840 in words is "one billion, two hundred twenty million, six hundred forty-three thousand, eight hundred forty".