661580189 has 2 divisors, whose sum is σ = 661580190. Its totient is φ = 661580188.

The previous prime is 661580167. The next prime is 661580191. The reversal of 661580189 is 981085166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 631516900 + 30063289 = 25130^2 + 5483^2 .

It is a cyclic number.

It is not a de Polignac number, because 661580189 - 2¹⁶ = 661514653 is a prime.

Together with 661580191, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661580149) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330790094 + 330790095.

It is an arithmetic number, because the mean of its divisors is an integer number (330790095).

Almost surely, 2^661580189 is an apocalyptic number.

It is an amenable number.

661580189 is a deficient number, since it is larger than the sum of its proper divisors (1).

661580189 is an equidigital number, since it uses as much as digits as its factorization.

661580189 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 103680, while the sum is 44.

The square root of 661580189 is about 25721.2011577998. The cubic root of 661580189 is about 871.3530665273.

The spelling of 661580189 in words is "six hundred sixty-one million, five hundred eighty thousand, one hundred eighty-nine".