20561185 has 4 divisors (see below), whose sum is σ = 24673428. Its totient is φ = 16448944.

The previous prime is 20561179. The next prime is 20561201. The reversal of 20561185 is 58116502.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 58116502 = 2 ⋅29058251.

It can be written as a sum of positive squares in 2 ways, for example, as 9585216 + 10975969 = 3096^2 + 3313^2 .

It is a cyclic number.

It is not a de Polignac number, because 20561185 - 2¹³ = 20552993 is a prime.

It is a Duffinian number.

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 3 ways as a sum of consecutive naturals, for example, 2056114 + ... + 2056123.

It is an arithmetic number, because the mean of its divisors is an integer number (6168357).

Almost surely, 2^20561185 is an apocalyptic number.

It is an amenable number.

20561185 is a deficient number, since it is larger than the sum of its proper divisors (4112243).

20561185 is an equidigital number, since it uses as much as digits as its factorization.

20561185 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4112242.

The product of its (nonzero) digits is 2400, while the sum is 28.

The square root of 20561185 is about 4534.4442878924. Note that the first 3 decimals coincide. The cubic root of 20561185 is about 273.9571966810.

Adding to 20561185 its reverse (58116502), we get a palindrome (78677687).

The spelling of 20561185 in words is "twenty million, five hundred sixty-one thousand, one hundred eighty-five".