21642256064 has 224 divisors, whose sum is σ = 52185978432. Its totient is φ = 8773632000.

The previous prime is 21642256057. The next prime is 21642256067. The reversal of 21642256064 is 46065224612.

It is not an unprimeable number, because it can be changed into a prime (21642256067) 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 31 ways as a sum of consecutive naturals, for example, 51406574 + ... + 51406994.

It is an arithmetic number, because the mean of its divisors is an integer number (232973118).

Almost surely, 2^21642256064 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 21642256064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26092989216).

21642256064 is an abundant number, since it is smaller than the sum of its proper divisors (30543722368).

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

21642256064 is a wasteful number, since it uses less digits than its factorization.

21642256064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 635 (or 625 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 38.

The spelling of 21642256064 in words is "twenty-one billion, six hundred forty-two million, two hundred fifty-six thousand, sixty-four".