21470671856 has 80 divisors (see below), whose sum is σ = 44077089600. Its totient is φ = 10111309824.

The previous prime is 21470671841. The next prime is 21470671861. The reversal of 21470671856 is 65817607412.

It is a self number, because there is not a number n which added to its sum of digits gives 21470671856.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8809070 + ... + 8811506.

It is an arithmetic number, because the mean of its divisors is an integer number (550963620).

Almost surely, 2^21470671856 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 21470671856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22038544800).

21470671856 is an abundant number, since it is smaller than the sum of its proper divisors (22606417744).

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

21470671856 is a wasteful number, since it uses less digits than its factorization.

21470671856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2826 (or 2820 counting only the distinct ones).

The product of its (nonzero) digits is 564480, while the sum is 47.

The spelling of 21470671856 in words is "twenty-one billion, four hundred seventy million, six hundred seventy-one thousand, eight hundred fifty-six".