21047273856 has 192 divisors, whose sum is σ = 71605591200. Its totient is φ = 5806080000.

The previous prime is 21047273851. The next prime is 21047273857. The reversal of 21047273856 is 65837274012.

It is a tau number, because it is divible by the number of its divisors (192).

It is a super-2 number, since 2×21047273856² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21047273851) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 188856 + ... + 278856.

Almost surely, 2^21047273856 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 21047273856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35802795600).

21047273856 is an abundant number, since it is smaller than the sum of its proper divisors (50558317344).

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

21047273856 is a wasteful number, since it uses less digits than its factorization.

21047273856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90057 (or 90042 counting only the distinct ones).

The product of its (nonzero) digits is 564480, while the sum is 45.

The spelling of 21047273856 in words is "twenty-one billion, forty-seven million, two hundred seventy-three thousand, eight hundred fifty-six".