1661616613 has 2 divisors, whose sum is σ = 1661616614. Its totient is φ = 1661616612.

The previous prime is 1661616599. The next prime is 1661616641. The reversal of 1661616613 is 3166161661.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 949687489 + 711929124 = 30817^2 + 26682^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1661616613 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1661616673) 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, 830808306 + 830808307.

It is an arithmetic number, because the mean of its divisors is an integer number (830808307).

Almost surely, 2^1661616613 is an apocalyptic number.

It is an amenable number.

1661616613 is a deficient number, since it is larger than the sum of its proper divisors (1).

1661616613 is an equidigital number, since it uses as much as digits as its factorization.

1661616613 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23328, while the sum is 37.

The square root of 1661616613 is about 40762.9318499050. The cubic root of 1661616613 is about 1184.4323898303.

The spelling of 1661616613 in words is "one billion, six hundred sixty-one million, six hundred sixteen thousand, six hundred thirteen".