21011168640 has 768 divisors, whose sum is σ = 86400691200. Its totient is φ = 4293918720.

The previous prime is 21011168599. The next prime is 21011168641. The reversal of 21011168640 is 4686111012.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 21011168598 and 21011168607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011168641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 81755392 + ... + 81755648.

It is an arithmetic number, because the mean of its divisors is an integer number (112500900).

Almost surely, 2^21011168640 is an apocalyptic number.

21011168640 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 21011168640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43200345600).

21011168640 is an abundant number, since it is smaller than the sum of its proper divisors (65389522560).

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

21011168640 is a wasteful number, since it uses less digits than its factorization.

21011168640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 383 (or 364 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 30.

Adding to 21011168640 its reverse (4686111012), we get a palindrome (25697279652).

The spelling of 21011168640 in words is "twenty-one billion, eleven million, one hundred sixty-eight thousand, six hundred forty".