19721716880 has 20 divisors (see below), whose sum is σ = 45852991932. Its totient is φ = 7888686720.

The previous prime is 19721716879. The next prime is 19721716909. The reversal of 19721716880 is 8861712791.

It can be written as a sum of positive squares in 2 ways, for example, as 2954574736 + 16767142144 = 54356^2 + 129488^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×19721716880² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 123260651 + ... + 123260810.

Almost surely, 2^19721716880 is an apocalyptic number.

19721716880 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19721716880 is an abundant number, since it is smaller than the sum of its proper divisors (26131275052).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

19721716880 is a wasteful number, since it uses less digits than its factorization.

19721716880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 246521474 (or 246521468 counting only the distinct ones).

The product of its (nonzero) digits is 338688, while the sum is 50.

The spelling of 19721716880 in words is "nineteen billion, seven hundred twenty-one million, seven hundred sixteen thousand, eight hundred eighty".