1640085720 has 256 divisors, whose sum is σ = 6265728000. Its totient is φ = 334043136.

The previous prime is 1640085709. The next prime is 1640085739. The reversal of 1640085720 is 275800461.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 314091 + ... + 319269.

It is an arithmetic number, because the mean of its divisors is an integer number (24475500).

Almost surely, 2^1640085720 is an apocalyptic number.

1640085720 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 1640085720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3132864000).

1640085720 is an abundant number, since it is smaller than the sum of its proper divisors (4625642280).

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

1640085720 is a wasteful number, since it uses less digits than its factorization.

1640085720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5242 (or 5238 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 1640085720 is about 40497.9718010668. The cubic root of 1640085720 is about 1179.2942538439.

The spelling of 1640085720 in words is "one billion, six hundred forty million, eighty-five thousand, seven hundred twenty".