205999920 has 180 divisors, whose sum is σ = 804903840. Its totient is φ = 47077632.

The previous prime is 205999909. The next prime is 205999943. The reversal of 205999920 is 29999502.

It is a tau number, because it is divible by the number of its divisors (180).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 32361 + ... + 38199.

It is an arithmetic number, because the mean of its divisors is an integer number (4471688).

Almost surely, 2^205999920 is an apocalyptic number.

205999920 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 205999920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (402451920).

205999920 is an abundant number, since it is smaller than the sum of its proper divisors (598903920).

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

205999920 is a wasteful number, since it uses less digits than its factorization.

205999920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5872 (or 5856 counting only the distinct ones).

The product of its (nonzero) digits is 131220, while the sum is 45.

The square root of 205999920 is about 14352.6973074750. The cubic root of 205999920 is about 590.5939819101.

The spelling of 205999920 in words is "two hundred five million, nine hundred ninety-nine thousand, nine hundred twenty".