21432729648 has 80 divisors (see below), whose sum is σ = 60458023296. Its totient is φ = 6488670720.

The previous prime is 21432729599. The next prime is 21432729649. The reversal of 21432729648 is 84692723412.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a junction number, because it is equal to n+sod(n) for n = 21432729597 and 21432729606.

It is not an unprimeable number, because it can be changed into a prime (21432729649) 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 15 ways as a sum of consecutive naturals, for example, 560715 + ... + 597717.

Almost surely, 2^21432729648 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21432729648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30229011648).

21432729648 is an abundant number, since it is smaller than the sum of its proper divisors (39025293648).

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

21432729648 is a wasteful number, since it uses less digits than its factorization.

21432729648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38122 (or 38116 counting only the distinct ones).

The product of its digits is 1161216, while the sum is 48.

The spelling of 21432729648 in words is "twenty-one billion, four hundred thirty-two million, seven hundred twenty-nine thousand, six hundred forty-eight".