1661500609 has 2 divisors, whose sum is σ = 1661500610. Its totient is φ = 1661500608.

The previous prime is 1661500591. The next prime is 1661500637. The reversal of 1661500609 is 9060051661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1361241025 + 300259584 = 36895^2 + 17328^2 .

It is a cyclic number.

It is not a de Polignac number, because 1661500609 - 2⁷ = 1661500481 is a prime.

It is not a weakly prime, because it can be changed into another prime (1661500669) 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, 830750304 + 830750305.

It is an arithmetic number, because the mean of its divisors is an integer number (830750305).

Almost surely, 2^1661500609 is an apocalyptic number.

It is an amenable number.

1661500609 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661500609 is an equidigital number, since it uses as much as digits as its factorization.

1661500609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 1661500609 is about 40761.5089146611. The cubic root of 1661500609 is about 1184.4048258922.

The spelling of 1661500609 in words is "one billion, six hundred sixty-one million, five hundred thousand, six hundred nine".