204055661 has 4 divisors (see below), whose sum is σ = 204216732. Its totient is φ = 203894592.

The previous prime is 204055637. The next prime is 204055673. The reversal of 204055661 is 166550402.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 166550402 = 2 ⋅83275201.

It can be written as a sum of positive squares in 2 ways, for example, as 47955625 + 156100036 = 6925^2 + 12494^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-204055661 is a prime.

It is a super-2 number, since 2×204055661² = 83277425572293842, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (204055601) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 78620 + ... + 81173.

It is an arithmetic number, because the mean of its divisors is an integer number (51054183).

Almost surely, 2^204055661 is an apocalyptic number.

It is an amenable number.

204055661 is a deficient number, since it is larger than the sum of its proper divisors (161071).

204055661 is a wasteful number, since it uses less digits than its factorization.

204055661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161070.

The product of its (nonzero) digits is 7200, while the sum is 29.

The square root of 204055661 is about 14284.8052489350. The cubic root of 204055661 is about 588.7300665655.

The spelling of 204055661 in words is "two hundred four million, fifty-five thousand, six hundred sixty-one".