21055833216 has 384 divisors, whose sum is σ = 68207106240. Its totient is φ = 6180495360.

The previous prime is 21055833179. The next prime is 21055833223. The reversal of 21055833216 is 61233855012.

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

It is a super-2 number, since 2×21055833216² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 71862766 + ... + 71863058.

Almost surely, 2^21055833216 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 21055833216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34103553120).

21055833216 is an abundant number, since it is smaller than the sum of its proper divisors (47151273024).

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

21055833216 is a wasteful number, since it uses less digits than its factorization.

21055833216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 484 (or 469 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 36.

The spelling of 21055833216 in words is "twenty-one billion, fifty-five million, eight hundred thirty-three thousand, two hundred sixteen".