21047967438464 has 128 divisors (see below), whose sum is σ = 43344095995200. Its totient is φ = 10174881153024.

The previous prime is 21047967438431. The next prime is 21047967438469. The reversal of 21047967438464 is 46483476974012.

It is a tau number, because it is divible by the number of its divisors (128).

It is a self number, because there is not a number n which added to its sum of digits gives 21047967438464.

It is not an unprimeable number, because it can be changed into a prime (21047967438469) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 257783054 + ... + 257864690.

Almost surely, 2^{21047967438464} 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 21047967438464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21672047997600).

21047967438464 is an abundant number, since it is smaller than the sum of its proper divisors (22296128556736).

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

21047967438464 is a wasteful number, since it uses less digits than its factorization.

21047967438464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82170 (or 82158 counting only the distinct ones).

The product of its (nonzero) digits is 195084288, while the sum is 65.

The spelling of 21047967438464 in words is "twenty-one trillion, forty-seven billion, nine hundred sixty-seven million, four hundred thirty-eight thousand, four hundred sixty-four".