19809659661 has 16 divisors (see below), whose sum is σ = 29219885568. Its totient is φ = 11836756400.

The previous prime is 19809659657. The next prime is 19809659689. The reversal of 19809659661 is 16695690891.

It is a cyclic number.

It is not a de Polignac number, because 19809659661 - 2² = 19809659657 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 19809659595 and 19809659604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19809659641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4225071 + ... + 4229756.

It is an arithmetic number, because the mean of its divisors is an integer number (1826242848).

Almost surely, 2^19809659661 is an apocalyptic number.

19809659661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

19809659661 is a deficient number, since it is larger than the sum of its proper divisors (9410225907).

19809659661 is a wasteful number, since it uses less digits than its factorization.

19809659661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8454912.

The product of its (nonzero) digits is 6298560, while the sum is 60.

The spelling of 19809659661 in words is "nineteen billion, eight hundred nine million, six hundred fifty-nine thousand, six hundred sixty-one".