21666547320 has 256 divisors, whose sum is σ = 73044633600. Its totient is φ = 5095157760.

The previous prime is 21666547291. The next prime is 21666547327. The reversal of 21666547320 is 2374566612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21666547327) 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 63 ways as a sum of consecutive naturals, for example, 30133921 + ... + 30134639.

It is an arithmetic number, because the mean of its divisors is an integer number (285330600).

Almost surely, 2^21666547320 is an apocalyptic number.

21666547320 is a gapful number since it is divisible by the number (20) 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 21666547320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36522316800).

21666547320 is an abundant number, since it is smaller than the sum of its proper divisors (51378086280).

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

21666547320 is a wasteful number, since it uses less digits than its factorization.

21666547320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1398 (or 1394 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 42.

The spelling of 21666547320 in words is "twenty-one billion, six hundred sixty-six million, five hundred forty-seven thousand, three hundred twenty".