19721433984 has 384 divisors, whose sum is σ = 64932710400. Its totient is φ = 5192318976.

The previous prime is 19721433947. The next prime is 19721434039. The reversal of 19721433984 is 48933412791.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (384).

It is a super-2 number, since 2×19721433984² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 41171857 + ... + 41172335.

It is an arithmetic number, because the mean of its divisors is an integer number (169095600).

Almost surely, 2^19721433984 is an apocalyptic number.

19721433984 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19721433984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32466355200).

19721433984 is an abundant number, since it is smaller than the sum of its proper divisors (45211276416).

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

19721433984 is a wasteful number, since it uses less digits than its factorization.

19721433984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 590 (or 561 counting only the distinct ones).

The product of its digits is 1306368, while the sum is 51.

The spelling of 19721433984 in words is "nineteen billion, seven hundred twenty-one million, four hundred thirty-three thousand, nine hundred eighty-four".