21671312512 has 64 divisors (see below), whose sum is σ = 43613568000. Its totient is φ = 10725571584.

The previous prime is 21671312491. The next prime is 21671312557. The reversal of 21671312512 is 21521317612.

It is a tau number, because it is divible by the number of its divisors (64).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8500614 + ... + 8503162.

It is an arithmetic number, because the mean of its divisors is an integer number (681462000).

Almost surely, 2^21671312512 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 21671312512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21806784000).

21671312512 is an abundant number, since it is smaller than the sum of its proper divisors (21942255488).

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

21671312512 is a wasteful number, since it uses less digits than its factorization.

21671312512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3213 (or 3201 counting only the distinct ones).

The product of its digits is 5040, while the sum is 31.

The spelling of 21671312512 in words is "twenty-one billion, six hundred seventy-one million, three hundred twelve thousand, five hundred twelve".