21666572313408 has 672 divisors, whose sum is σ = 71731168704000. Its totient is φ = 6183883837440.

The previous prime is 21666572313403. The next prime is 21666572313431. The reversal of 21666572313408 is 80431327566612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21666572313403) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 21262582723 + ... + 21262583741.

Almost surely, 2^{21666572313408} 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 21666572313408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35865584352000).

21666572313408 is an abundant number, since it is smaller than the sum of its proper divisors (50064596390592).

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

21666572313408 is a wasteful number, since it uses less digits than its factorization.

21666572313408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1923 (or 1910 counting only the distinct ones).

The product of its (nonzero) digits is 8709120, while the sum is 54.

The spelling of 21666572313408 in words is "twenty-one trillion, six hundred sixty-six billion, five hundred seventy-two million, three hundred thirteen thousand, four hundred eight".