19708108661 has 2 divisors, whose sum is σ = 19708108662. Its totient is φ = 19708108660.

The previous prime is 19708108649. The next prime is 19708108669. The reversal of 19708108661 is 16680180791.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14625274225 + 5082834436 = 120935^2 + 71294^2 .

It is a cyclic number.

It is not a de Polignac number, because 19708108661 - 2¹⁸ = 19707846517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19708108669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9854054330 + 9854054331.

It is an arithmetic number, because the mean of its divisors is an integer number (9854054331).

Almost surely, 2^19708108661 is an apocalyptic number.

It is an amenable number.

19708108661 is a deficient number, since it is larger than the sum of its proper divisors (1).

19708108661 is an equidigital number, since it uses as much as digits as its factorization.

19708108661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 145152, while the sum is 47.

The spelling of 19708108661 in words is "nineteen billion, seven hundred eight million, one hundred eight thousand, six hundred sixty-one".