205779840 has 256 divisors, whose sum is σ = 764951040. Its totient is φ = 46080000.

The previous prime is 205779817. The next prime is 205779841. The reversal of 205779840 is 48977502.

205779840 is digitally balanced in base 3, 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 (42).

It is a junction number, because it is equal to n+sod(n) for n = 205779792 and 205779801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205779841) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 819715 + ... + 819965.

It is an arithmetic number, because the mean of its divisors is an integer number (2988090).

Almost surely, 2^205779840 is an apocalyptic number.

205779840 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 205779840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (382475520).

205779840 is an abundant number, since it is smaller than the sum of its proper divisors (559171200).

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

205779840 is a wasteful number, since it uses less digits than its factorization.

205779840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 341 (or 329 counting only the distinct ones).

The product of its (nonzero) digits is 141120, while the sum is 42.

The square root of 205779840 is about 14345.0284070824. The cubic root of 205779840 is about 590.3835866208.

The spelling of 205779840 in words is "two hundred five million, seven hundred seventy-nine thousand, eight hundred forty".