21218644392 has 192 divisors, whose sum is σ = 59919048000. Its totient is φ = 6209433600.

The previous prime is 21218644379. The next prime is 21218644409. The reversal of 21218644392 is 29344681212.

It is a happy 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 47 ways as a sum of consecutive naturals, for example, 60798234 + ... + 60798582.

It is an arithmetic number, because the mean of its divisors is an integer number (312078375).

Almost surely, 2^21218644392 is an apocalyptic number.

21218644392 is a gapful number since it is divisible by the number (22) 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 21218644392, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29959524000).

21218644392 is an abundant number, since it is smaller than the sum of its proper divisors (38700403608).

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

21218644392 is a wasteful number, since it uses less digits than its factorization.

21218644392 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 588 (or 543 counting only the distinct ones).

The product of its digits is 165888, while the sum is 42.

The spelling of 21218644392 in words is "twenty-one billion, two hundred eighteen million, six hundred forty-four thousand, three hundred ninety-two".