19650663991 has 6 divisors (see below), whose sum is σ = 22858935720. Its totient is φ = 16843426236.

The previous prime is 19650663979. The next prime is 19650664009. The reversal of 19650663991 is 19936605691.

It is not a de Polignac number, because 19650663991 - 2¹⁹ = 19650139703 is a prime.

It is a super-2 number, since 2×19650663991² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19650663961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 200516931 + ... + 200517028.

It is an arithmetic number, because the mean of its divisors is an integer number (3809822620).

Almost surely, 2^19650663991 is an apocalyptic number.

19650663991 is a deficient number, since it is larger than the sum of its proper divisors (3208271729).

19650663991 is an equidigital number, since it uses as much as digits as its factorization.

19650663991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 401033973 (or 401033966 counting only the distinct ones).

The product of its (nonzero) digits is 2361960, while the sum is 55.

The spelling of 19650663991 in words is "nineteen billion, six hundred fifty million, six hundred sixty-three thousand, nine hundred ninety-one".