205561216 has 64 divisors (see below), whose sum is σ = 475817760. Its totient is φ = 86630400.

The previous prime is 205561207. The next prime is 205561241. The reversal of 205561216 is 612165502.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (28).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 52776 + ... + 56536.

Almost surely, 2^205561216 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 205561216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (237908880).

205561216 is an abundant number, since it is smaller than the sum of its proper divisors (270256544).

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

205561216 is an equidigital number, since it uses as much as digits as its factorization.

205561216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3843 (or 3831 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 205561216 is about 14337.4061810357. The cubic root of 205561216 is about 590.1744346817.

It can be divided in two parts, 205561 and 216, that multiplied together give a triangular number (44401176 = T₉₄₂₃).

The spelling of 205561216 in words is "two hundred five million, five hundred sixty-one thousand, two hundred sixteen".