21291363216 has 200 divisors, whose sum is σ = 66250462080. Its totient is φ = 6580175616.

The previous prime is 21291363209. The next prime is 21291363253. The reversal of 21291363216 is 61236319212.

21291363216 is a `hidden beast` number, since 2 + 1 + 2 + 9 + 1 + 3 + 632 + 16 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 1148130 + ... + 1166526.

Almost surely, 2^21291363216 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 21291363216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33125231040).

21291363216 is an abundant number, since it is smaller than the sum of its proper divisors (44959098864).

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

21291363216 is a wasteful number, since it uses less digits than its factorization.

21291363216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18483 (or 18468 counting only the distinct ones).

The product of its digits is 23328, while the sum is 36.

The spelling of 21291363216 in words is "twenty-one billion, two hundred ninety-one million, three hundred sixty-three thousand, two hundred sixteen".