21728609280 has 1056 divisors, whose sum is σ = 92703356928. Its totient is φ = 4600627200.

The previous prime is 21728609269. The next prime is 21728609297. The reversal of 21728609280 is 8290682712.

21728609280 is a `hidden beast` number, since 2 + 17 + 2 + 8 + 609 + 28 + 0 = 666.

It is a super-2 number, since 2×21728609280² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 409973734 + ... + 409973786.

Almost surely, 2^21728609280 is an apocalyptic number.

21728609280 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 21728609280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46351678464).

21728609280 is an abundant number, since it is smaller than the sum of its proper divisors (70974747648).

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

21728609280 is a wasteful number, since it uses less digits than its factorization.

21728609280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163 (or 142 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 45.

The spelling of 21728609280 in words is "twenty-one billion, seven hundred twenty-eight million, six hundred nine thousand, two hundred eighty".