21689138016 has 672 divisors, whose sum is σ = 83569485888. Its totient is φ = 5374771200.

The previous prime is 21689137973. The next prime is 21689138057. The reversal of 21689138016 is 61083198612.

It is a tau number, because it is divible by the number of its divisors (672).

It is a congruent number.

It is an unprimeable number.

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 111 ways as a sum of consecutive naturals, for example, 36088116 + ... + 36088716.

It is an arithmetic number, because the mean of its divisors is an integer number (124359354).

Almost surely, 2^21689138016 is an apocalyptic number.

21689138016 is a gapful number since it is divisible by the number (26) 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 21689138016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41784742944).

21689138016 is an abundant number, since it is smaller than the sum of its proper divisors (61880347872).

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

21689138016 is a wasteful number, since it uses less digits than its factorization.

21689138016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 666 (or 643 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The spelling of 21689138016 in words is "twenty-one billion, six hundred eighty-nine million, one hundred thirty-eight thousand, sixteen".