19864636789 has 2 divisors, whose sum is σ = 19864636790. Its totient is φ = 19864636788.

The previous prime is 19864636787. The next prime is 19864636811. The reversal of 19864636789 is 98763646891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14630837764 + 5233799025 = 120958^2 + 72345^2 .

It is a cyclic number.

It is not a de Polignac number, because 19864636789 - 2¹ = 19864636787 is a prime.

Together with 19864636787, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19864636787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9932318394 + 9932318395.

It is an arithmetic number, because the mean of its divisors is an integer number (9932318395).

Almost surely, 2^19864636789 is an apocalyptic number.

It is an amenable number.

19864636789 is a deficient number, since it is larger than the sum of its proper divisors (1).

19864636789 is an equidigital number, since it uses as much as digits as its factorization.

19864636789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 94058496, while the sum is 67.

The spelling of 19864636789 in words is "nineteen billion, eight hundred sixty-four million, six hundred thirty-six thousand, seven hundred eighty-nine".