21218925168 has 480 divisors, whose sum is σ = 72578068992. Its totient is φ = 5660928000.

The previous prime is 21218925163. The next prime is 21218925179. The reversal of 21218925168 is 86152981212.

21218925168 is a `hidden beast` number, since 2 + 121 + 8 + 9 + 2 + 516 + 8 = 666.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21218925163) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 161976463 + ... + 161976593.

Almost surely, 2^21218925168 is an apocalyptic number.

21218925168 is a gapful number since it is divisible by the number (28) 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 21218925168, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36289034496).

21218925168 is an abundant number, since it is smaller than the sum of its proper divisors (51359143824).

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

21218925168 is a wasteful number, since it uses less digits than its factorization.

21218925168 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333 (or 324 counting only the distinct ones).

The product of its digits is 138240, while the sum is 45.

The spelling of 21218925168 in words is "twenty-one billion, two hundred eighteen million, nine hundred twenty-five thousand, one hundred sixty-eight".