19871649697 has 2 divisors, whose sum is σ = 19871649698. Its totient is φ = 19871649696.

The previous prime is 19871649661. The next prime is 19871649731. The reversal of 19871649697 is 79694617891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19187513361 + 684136336 = 138519^2 + 26156^2 .

It is a cyclic number.

It is not a de Polignac number, because 19871649697 - 2¹⁵ = 19871616929 is a prime.

It is not a weakly prime, because it can be changed into another prime (19871649797) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9935824848 + 9935824849.

It is an arithmetic number, because the mean of its divisors is an integer number (9935824849).

Almost surely, 2^19871649697 is an apocalyptic number.

It is an amenable number.

19871649697 is a deficient number, since it is larger than the sum of its proper divisors (1).

19871649697 is an equidigital number, since it uses as much as digits as its factorization.

19871649697 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 41150592, while the sum is 67.

The spelling of 19871649697 in words is "nineteen billion, eight hundred seventy-one million, six hundred forty-nine thousand, six hundred ninety-seven".