21264568416 has 720 divisors, whose sum is σ = 80151637104. Its totient is φ = 5502422016.

The previous prime is 21264568393. The next prime is 21264568417. The reversal of 21264568416 is 61486546212.

It is a happy number.

21264568416 is a `hidden beast` number, since 2 + 12 + 64 + 568 + 4 + 16 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21264568417) 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 119 ways as a sum of consecutive naturals, for example, 401218246 + ... + 401218298.

Almost surely, 2^21264568416 is an apocalyptic number.

21264568416 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 21264568416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40075818552).

21264568416 is an abundant number, since it is smaller than the sum of its proper divisors (58887068688).

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

21264568416 is an frugal number, since it uses more digits than its factorization.

21264568416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117 (or 78 counting only the distinct ones).

The product of its digits is 552960, while the sum is 45.

The spelling of 21264568416 in words is "twenty-one billion, two hundred sixty-four million, five hundred sixty-eight thousand, four hundred sixteen".