20204561 has 8 divisors (see below), whose sum is σ = 22509480. Its totient is φ = 18006912.

The previous prime is 20204533. The next prime is 20204563. The reversal of 20204561 is 16540202.

20204561 = 869² + 870² + ... + 894².

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 712336 + 19492225 = 844^2 + 4415^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-20204561 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20204563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26420 + ... + 27173.

It is an arithmetic number, because the mean of its divisors is an integer number (2813685).

Almost surely, 2^20204561 is an apocalyptic number.

It is an amenable number.

20204561 is a deficient number, since it is larger than the sum of its proper divisors (2304919).

20204561 is a wasteful number, since it uses less digits than its factorization.

20204561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53635.

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 20204561 is about 4494.9483868005. The cubic root of 20204561 is about 272.3640642878.

Adding to 20204561 its reverse (16540202), we get a palindrome (36744763).

The spelling of 20204561 in words is "twenty million, two hundred four thousand, five hundred sixty-one".