19989765894649 has 2 divisors, whose sum is σ = 19989765894650. Its totient is φ = 19989765894648.

The previous prime is 19989765894619. The next prime is 19989765894673. The reversal of 19989765894649 is 94649856798991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14217726009600 + 5772039885049 = 3770640^2 + 2402507^2 .

It is a cyclic number.

It is not a de Polignac number, because 19989765894649 - 2⁷ = 19989765894521 is a prime.

It is not a weakly prime, because it can be changed into another prime (19989765894619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9994882947324 + 9994882947325.

It is an arithmetic number, because the mean of its divisors is an integer number (9994882947325).

Almost surely, 2^{19989765894649} is an apocalyptic number.

It is an amenable number.

19989765894649 is a deficient number, since it is larger than the sum of its proper divisors (1).

19989765894649 is an equidigital number, since it uses as much as digits as its factorization.

19989765894649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 76187381760, while the sum is 94.

The spelling of 19989765894649 in words is "nineteen trillion, nine hundred eighty-nine billion, seven hundred sixty-five million, eight hundred ninety-four thousand, six hundred forty-nine".