19881647641 has 2 divisors, whose sum is σ = 19881647642. Its totient is φ = 19881647640.

The previous prime is 19881647629. The next prime is 19881647647. The reversal of 19881647641 is 14674618891.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13183862041 + 6697785600 = 114821^2 + 81840^2 .

It is a cyclic number.

It is not a de Polignac number, because 19881647641 - 2²⁷ = 19747429913 is a prime.

It is not a weakly prime, because it can be changed into another prime (19881647647) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9940823820 + 9940823821.

It is an arithmetic number, because the mean of its divisors is an integer number (9940823821).

Almost surely, 2^19881647641 is an apocalyptic number.

It is an amenable number.

19881647641 is a deficient number, since it is larger than the sum of its proper divisors (1).

19881647641 is an equidigital number, since it uses as much as digits as its factorization.

19881647641 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2322432, while the sum is 55.

The spelling of 19881647641 in words is "nineteen billion, eight hundred eighty-one million, six hundred forty-seven thousand, six hundred forty-one".