21211715712 has 128 divisors (see below), whose sum is σ = 61536697920. Its totient is φ = 6420377600.

The previous prime is 21211715699. The next prime is 21211715719. The reversal of 21211715712 is 21751711212.

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 21211715712.

It is not an unprimeable number, because it can be changed into a prime (21211715719) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4479298 + ... + 4484030.

Almost surely, 2^21211715712 is an apocalyptic number.

21211715712 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21211715712, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30768348960).

21211715712 is an abundant number, since it is smaller than the sum of its proper divisors (40324982208).

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

21211715712 is a wasteful number, since it uses less digits than its factorization.

21211715712 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5822 (or 5810 counting only the distinct ones).

The product of its digits is 1960, while the sum is 30.

The spelling of 21211715712 in words is "twenty-one billion, two hundred eleven million, seven hundred fifteen thousand, seven hundred twelve".