21001053660 has 96 divisors (see below), whose sum is σ = 59449942272. Its totient is φ = 5539000320.

The previous prime is 21001053617. The next prime is 21001053679. The reversal of 21001053660 is 6635010012.

It is a self number, because there is not a number n which added to its sum of digits gives 21001053660.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2058492 + ... + 2068668.

It is an arithmetic number, because the mean of its divisors is an integer number (619270232).

Almost surely, 2^21001053660 is an apocalyptic number.

21001053660 is a gapful number since it is divisible by the number (20) 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 21001053660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29724971136).

21001053660 is an abundant number, since it is smaller than the sum of its proper divisors (38448888612).

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

21001053660 is a wasteful number, since it uses less digits than its factorization.

21001053660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10563 (or 10561 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 24.

Adding to 21001053660 its reverse (6635010012), we get a palindrome (27636063672).

The spelling of 21001053660 in words is "twenty-one billion, one million, fifty-three thousand, six hundred sixty".