19809659681 has 12 divisors (see below), whose sum is σ = 23046750720. Its totient is φ = 16977600360.

The previous prime is 19809659657. The next prime is 19809659689. The reversal of 19809659681 is 18695690891.

It is not a de Polignac number, because 19809659681 - 2¹⁸ = 19809397537 is a prime.

It is a super-2 number, since 2×19809659681² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (19809659689) 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 in 11 ways as a sum of consecutive naturals, for example, 473816 + ... + 513926.

It is an arithmetic number, because the mean of its divisors is an integer number (1920562560).

Almost surely, 2^19809659681 is an apocalyptic number.

It is an amenable number.

19809659681 is a deficient number, since it is larger than the sum of its proper divisors (3237091039).

19809659681 is a wasteful number, since it uses less digits than its factorization.

19809659681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50204 (or 50197 counting only the distinct ones).

The product of its (nonzero) digits is 8398080, while the sum is 62.

The spelling of 19809659681 in words is "nineteen billion, eight hundred nine million, six hundred fifty-nine thousand, six hundred eighty-one".