205809780320640 has 768 divisors, whose sum is σ = 783244375280640. Its totient is φ = 51463434240000.

The previous prime is 205809780320597. The next prime is 205809780320687. The reversal of 205809780320640 is 46023087908502.

205809780320640 is a `hidden beast` number, since 20 + 5 + 80 + 97 + 80 + 320 + 64 + 0 = 666.

205809780320640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 716337015 + ... + 716624265.

It is an arithmetic number, because the mean of its divisors is an integer number (1019849446980).

Almost surely, 2^{205809780320640} is an apocalyptic number.

205809780320640 is a gapful number since it is divisible by the number (20) 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 205809780320640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (391622187640320).

205809780320640 is an abundant number, since it is smaller than the sum of its proper divisors (577434594960000).

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

205809780320640 is a wasteful number, since it uses less digits than its factorization.

205809780320640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 287573 (or 287549 counting only the distinct ones).

The product of its (nonzero) digits is 5806080, while the sum is 54.

The spelling of 205809780320640 in words is "two hundred five trillion, eight hundred nine billion, seven hundred eighty million, three hundred twenty thousand, six hundred forty".