21554820550656 has 312 divisors, whose sum is σ = 62759124320256. Its totient is φ = 7127769415680.

The previous prime is 21554820550649. The next prime is 21554820550691. The reversal of 21554820550656 is 65605502845512.

21554820550656 is a `hidden beast` number, since 2 + 1 + 5 + 5 + 4 + 8 + 20 + 550 + 65 + 6 = 666.

It is a super-3 number, since 3×21554820550656³ (a number of 41 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2696708196 + ... + 2696716188.

It is an arithmetic number, because the mean of its divisors is an integer number (201151039488).

Almost surely, 2^{21554820550656} 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 21554820550656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31379562160128).

21554820550656 is an abundant number, since it is smaller than the sum of its proper divisors (41204303769600).

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

21554820550656 is a wasteful number, since it uses less digits than its factorization.

21554820550656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8597 (or 8572 counting only the distinct ones).

The product of its (nonzero) digits is 14400000, while the sum is 54.

The spelling of 21554820550656 in words is "twenty-one trillion, five hundred fifty-four billion, eight hundred twenty million, five hundred fifty thousand, six hundred fifty-six".