21697728000 has 320 divisors, whose sum is σ = 77697652032. Its totient is φ = 5340364800.

The previous prime is 21697727983. The next prime is 21697728001. The reversal of 21697728000 is 82779612.

It is a tau number, because it is divible by the number of its divisors (320).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21697728001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2491654 + ... + 2500346.

Almost surely, 2^21697728000 is an apocalyptic number.

21697728000 is a gapful number since it is divisible by the number (20) 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 21697728000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38848826016).

21697728000 is an abundant number, since it is smaller than the sum of its proper divisors (55999924032).

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

21697728000 is an equidigital number, since it uses as much as digits as its factorization.

21697728000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8742 (or 8716 counting only the distinct ones).

The product of its (nonzero) digits is 84672, while the sum is 42.

The spelling of 21697728000 in words is "twenty-one billion, six hundred ninety-seven million, seven hundred twenty-eight thousand".