1640686320 has 640 divisors, whose sum is σ = 7379527680. Its totient is φ = 325140480.

The previous prime is 1640686259. The next prime is 1640686331. The reversal of 1640686320 is 236860461.

1640686320 is a `hidden beast` number, since 1 + 640 + 6 + 8 + 6 + 3 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 3341275 + ... + 3341765.

It is an arithmetic number, because the mean of its divisors is an integer number (11530512).

Almost surely, 2^1640686320 is an apocalyptic number.

1640686320 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 1640686320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3689763840).

1640686320 is an abundant number, since it is smaller than the sum of its proper divisors (5738841360).

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

1640686320 is a wasteful number, since it uses less digits than its factorization.

1640686320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 550 (or 538 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 36.

The square root of 1640686320 is about 40505.3863084899. The cubic root of 1640686320 is about 1179.4381889403.

The spelling of 1640686320 in words is "one billion, six hundred forty million, six hundred eighty-six thousand, three hundred twenty".