21660994080 has 720 divisors, whose sum is σ = 88570722240. Its totient is φ = 4967930880.

The previous prime is 21660994037. The next prime is 21660994081. The reversal of 21660994080 is 8049906612.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (720).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (21660994081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 29794677 + ... + 29795403.

It is an arithmetic number, because the mean of its divisors is an integer number (123014892).

Almost surely, 2^21660994080 is an apocalyptic number.

21660994080 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 21660994080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (44285361120).

21660994080 is an abundant number, since it is smaller than the sum of its proper divisors (66909728160).

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

21660994080 is a wasteful number, since it uses less digits than its factorization.

21660994080 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 795 (or 767 counting only the distinct ones).

The product of its (nonzero) digits is 186624, while the sum is 45.

The spelling of 21660994080 in words is "twenty-one billion, six hundred sixty million, nine hundred ninety-four thousand, eighty".