19387661 has 2 divisors, whose sum is σ = 19387662. Its totient is φ = 19387660.

The previous prime is 19387649. The next prime is 19387703. The reversal of 19387661 is 16678391.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17682025 + 1705636 = 4205^2 + 1306^2 .

It is an emirp because it is prime and its reverse (16678391) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19387661 - 2¹⁰ = 19386637 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19387601) 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, 9693830 + 9693831.

It is an arithmetic number, because the mean of its divisors is an integer number (9693831).

Almost surely, 2^19387661 is an apocalyptic number.

It is an amenable number.

19387661 is a deficient number, since it is larger than the sum of its proper divisors (1).

19387661 is an equidigital number, since it uses as much as digits as its factorization.

19387661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 54432, while the sum is 41.

The square root of 19387661 is about 4403.1421734938. The cubic root of 19387661 is about 268.6427590154.

The spelling of 19387661 in words is "nineteen million, three hundred eighty-seven thousand, six hundred sixty-one".