1320644640 has 288 divisors, whose sum is σ = 4924644480. Its totient is φ = 291409920.

The previous prime is 1320644627. The next prime is 1320644657. The reversal of 1320644640 is 464460231.

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 = 1320644598 and 1320644607.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3228756 + ... + 3229164.

It is an arithmetic number, because the mean of its divisors is an integer number (17099460).

Almost surely, 2^1320644640 is an apocalyptic number.

1320644640 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 1320644640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2462322240).

1320644640 is an abundant number, since it is smaller than the sum of its proper divisors (3603999840).

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

1320644640 is a wasteful number, since it uses less digits than its factorization.

1320644640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 496 (or 457 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 30.

The square root of 1320644640 is about 36340.6747323161. The cubic root of 1320644640 is about 1097.1398534299.

The spelling of 1320644640 in words is "one billion, three hundred twenty million, six hundred forty-four thousand, six hundred forty".