204561491 has 2 divisors, whose sum is σ = 204561492. Its totient is φ = 204561490.

The previous prime is 204561439. The next prime is 204561521. The reversal of 204561491 is 194165402.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-204561491 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (204561421) 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 as a sum of consecutive naturals, namely, 102280745 + 102280746.

It is an arithmetic number, because the mean of its divisors is an integer number (102280746).

Almost surely, 2^204561491 is an apocalyptic number.

204561491 is a deficient number, since it is larger than the sum of its proper divisors (1).

204561491 is an equidigital number, since it uses as much as digits as its factorization.

204561491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 204561491 is about 14302.4994668764. The cubic root of 204561491 is about 589.2161293685.

It can be divided in two parts, 2045 and 61491, that added together give a palindrome (63536).

The spelling of 204561491 in words is "two hundred four million, five hundred sixty-one thousand, four hundred ninety-one".