19661317537 has 2 divisors, whose sum is σ = 19661317538. Its totient is φ = 19661317536.

The previous prime is 19661317531. The next prime is 19661317573. The reversal of 19661317537 is 73571316691.

Together with next prime (19661317573) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16245031936 + 3416285601 = 127456^2 + 58449^2 .

It is a cyclic number.

It is not a de Polignac number, because 19661317537 - 2¹⁹ = 19660793249 is a prime.

It is not a weakly prime, because it can be changed into another prime (19661317531) 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, 9830658768 + 9830658769.

It is an arithmetic number, because the mean of its divisors is an integer number (9830658769).

Almost surely, 2^19661317537 is an apocalyptic number.

It is an amenable number.

19661317537 is a deficient number, since it is larger than the sum of its proper divisors (1).

19661317537 is an equidigital number, since it uses as much as digits as its factorization.

19661317537 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 714420, while the sum is 49.

The spelling of 19661317537 in words is "nineteen billion, six hundred sixty-one million, three hundred seventeen thousand, five hundred thirty-seven".