19771387997 has 2 divisors, whose sum is σ = 19771387998. Its totient is φ = 19771387996.

The previous prime is 19771387927. The next prime is 19771388023. The reversal of 19771387997 is 79978317791.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14305595236 + 5465792761 = 119606^2 + 73931^2 .

It is an emirp because it is prime and its reverse (79978317791) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 19771387997 - 2¹⁸ = 19771125853 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19771387927) 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, 9885693998 + 9885693999.

It is an arithmetic number, because the mean of its divisors is an integer number (9885693999).

Almost surely, 2^19771387997 is an apocalyptic number.

It is an amenable number.

19771387997 is a deficient number, since it is larger than the sum of its proper divisors (1).

19771387997 is an equidigital number, since it uses as much as digits as its factorization.

19771387997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 42007896, while the sum is 68.

The spelling of 19771387997 in words is "nineteen billion, seven hundred seventy-one million, three hundred eighty-seven thousand, nine hundred ninety-seven".