205890100 has 72 divisors (see below), whose sum is σ = 485897720. Its totient is φ = 75271680.

The previous prime is 205890079. The next prime is 205890109. The reversal of 205890100 is 1098502.

It can be written as a sum of positive squares in 12 ways, for example, as 19731364 + 186158736 = 4442^2 + 13644^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205890109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 140974 + ... + 142426.

Almost surely, 2^205890100 is an apocalyptic number.

205890100 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 205890100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (242948860).

205890100 is an abundant number, since it is smaller than the sum of its proper divisors (280007620).

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

205890100 is a wasteful number, since it uses less digits than its factorization.

205890100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1589 (or 1582 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 205890100 is about 14348.8710357296. The cubic root of 205890100 is about 590.4890133255.

The spelling of 205890100 in words is "two hundred five million, eight hundred ninety thousand, one hundred".