21729596544 has 384 divisors, whose sum is σ = 69236294400. Its totient is φ = 6764000256.

The previous prime is 21729596531. The next prime is 21729596593. The reversal of 21729596544 is 44569592712.

It is a happy number.

21729596544 is a `hidden beast` number, since 2 + 1 + 7 + 2 + 9 + 5 + 96 + 544 = 666.

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

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 49050787 + ... + 49051229.

It is an arithmetic number, because the mean of its divisors is an integer number (180302850).

Almost surely, 2^21729596544 is an apocalyptic number.

21729596544 is a gapful number since it is divisible by the number (24) 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 21729596544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34618147200).

21729596544 is an abundant number, since it is smaller than the sum of its proper divisors (47506697856).

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

21729596544 is an equidigital number, since it uses as much as digits as its factorization.

21729596544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 574 (or 550 counting only the distinct ones).

The product of its digits is 5443200, while the sum is 54.

The spelling of 21729596544 in words is "twenty-one billion, seven hundred twenty-nine million, five hundred ninety-six thousand, five hundred forty-four".