21320106606 has 128 divisors (see below), whose sum is σ = 52915161600. Its totient is φ = 6323443200.

The previous prime is 21320106571. The next prime is 21320106637. The reversal of 21320106606 is 60660102312.

21320106606 is a `hidden beast` number, since 21 + 3 + 20 + 10 + 6 + 606 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21320106606.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 11214256 + ... + 11216156.

It is an arithmetic number, because the mean of its divisors is an integer number (413399700).

Almost surely, 2^21320106606 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21320106606, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26457580800).

21320106606 is an abundant number, since it is smaller than the sum of its proper divisors (31595054994).

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

21320106606 is a wasteful number, since it uses less digits than its factorization.

21320106606 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2591 (or 2585 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

Adding to 21320106606 its reverse (60660102312), we get a palindrome (81980208918).

The spelling of 21320106606 in words is "twenty-one billion, three hundred twenty million, one hundred six thousand, six hundred six".