19861616891 has 2 divisors, whose sum is σ = 19861616892. Its totient is φ = 19861616890.

The previous prime is 19861616867. The next prime is 19861616927.

19861616891 is nontrivially palindromic in base 10.

It is a weak prime.

It is a palprime.

It is a cyclic number.

It is not a de Polignac number, because 19861616891 - 2²² = 19857422587 is a prime.

It is not a weakly prime, because it can be changed into another prime (19861616591) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9930808445 + 9930808446.

It is an arithmetic number, because the mean of its divisors is an integer number (9930808446).

Almost surely, 2^19861616891 is an apocalyptic number.

19861616891 is a deficient number, since it is larger than the sum of its proper divisors (1).

19861616891 is an equidigital number, since it uses as much as digits as its factorization.

19861616891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1119744, while the sum is 56.

The spelling of 19861616891 in words is "nineteen billion, eight hundred sixty-one million, six hundred sixteen thousand, eight hundred ninety-one".