21006686591744 has 144 divisors (see below), whose sum is σ = 50454462938880. Its totient is φ = 8527208878080.

The previous prime is 21006686591701. The next prime is 21006686591767. The reversal of 21006686591744 is 44719568660012.

It is a happy number.

It is a super-3 number, since 3×21006686591744³ (a number of 41 digits) contains 333 as substring.

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, 165443867 + ... + 165570789.

Almost surely, 2^{21006686591744} 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 21006686591744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25227231469440).

21006686591744 is an abundant number, since it is smaller than the sum of its proper divisors (29447776347136).

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

21006686591744 is a wasteful number, since it uses less digits than its factorization.

21006686591744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 131826 (or 131812 counting only the distinct ones).

The product of its (nonzero) digits is 17418240, while the sum is 59.

The spelling of 21006686591744 in words is "twenty-one trillion, six billion, six hundred eighty-six million, five hundred ninety-one thousand, seven hundred forty-four".