19985727997 has 2 divisors, whose sum is σ = 19985727998. Its totient is φ = 19985727996.

The previous prime is 19985727991. The next prime is 19985728019. The reversal of 19985727997 is 79972758991.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19950432516 + 35295481 = 141246^2 + 5941^2 .

It is an emirp because it is prime and its reverse (79972758991) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19985727997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19985727991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9992863998 + 9992863999.

It is an arithmetic number, because the mean of its divisors is an integer number (9992863999).

Almost surely, 2^19985727997 is an apocalyptic number.

It is an amenable number.

19985727997 is a deficient number, since it is larger than the sum of its proper divisors (1).

19985727997 is an equidigital number, since it uses as much as digits as its factorization.

19985727997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 180033840, while the sum is 73.

The spelling of 19985727997 in words is "nineteen billion, nine hundred eighty-five million, seven hundred twenty-seven thousand, nine hundred ninety-seven".