21342064656 has 320 divisors, whose sum is σ = 66415749120. Its totient is φ = 5829304320.

The previous prime is 21342064649. The next prime is 21342064657. The reversal of 21342064656 is 65646024312.

It is not an unprimeable number, because it can be changed into a prime (21342064657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 42429301 + ... + 42429803.

It is an arithmetic number, because the mean of its divisors is an integer number (207549216).

Almost surely, 2^21342064656 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 21342064656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33207874560).

21342064656 is an abundant number, since it is smaller than the sum of its proper divisors (45073684464).

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

21342064656 is a wasteful number, since it uses less digits than its factorization.

21342064656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 734 (or 728 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 39.

Adding to 21342064656 its reverse (65646024312), we get a palindrome (86988088968).

The spelling of 21342064656 in words is "twenty-one billion, three hundred forty-two million, sixty-four thousand, six hundred fifty-six".