21864513216 has 224 divisors, whose sum is σ = 71459555328. Its totient is φ = 5745438720.

The previous prime is 21864513163. The next prime is 21864513217. The reversal of 21864513216 is 61231546812.

It is a tau number, because it is divible by the number of its divisors (224).

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (21864513217) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 5117161 + ... + 5121431.

It is an arithmetic number, because the mean of its divisors is an integer number (319015872).

Almost surely, 2^21864513216 is an apocalyptic number.

21864513216 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 21864513216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35729777664).

21864513216 is an abundant number, since it is smaller than the sum of its proper divisors (49595042112).

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

21864513216 is a wasteful number, since it uses less digits than its factorization.

21864513216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4599 (or 4589 counting only the distinct ones).

The product of its digits is 69120, while the sum is 39.

The spelling of 21864513216 in words is "twenty-one billion, eight hundred sixty-four million, five hundred thirteen thousand, two hundred sixteen".