21549856608 has 432 divisors, whose sum is σ = 77273436240. Its totient is φ = 5657444352.

The previous prime is 21549856583. The next prime is 21549856637. The reversal of 21549856608 is 80665894512.

21549856608 is a `hidden beast` number, since 21 + 5 + 4 + 9 + 8 + 5 + 6 + 608 = 666.

It is a super-2 number, since 2×21549856608² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 10314828 + ... + 10316916.

It is an arithmetic number, because the mean of its divisors is an integer number (178873695).

Almost surely, 2^21549856608 is an apocalyptic number.

21549856608 is a gapful number since it is divisible by the number (28) 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 21549856608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38636718120).

21549856608 is an abundant number, since it is smaller than the sum of its proper divisors (55723579632).

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

21549856608 is a wasteful number, since it uses less digits than its factorization.

21549856608 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2179 (or 2161 counting only the distinct ones).

The product of its (nonzero) digits is 4147200, while the sum is 54.

The spelling of 21549856608 in words is "twenty-one billion, five hundred forty-nine million, eight hundred fifty-six thousand, six hundred eight".