21809594880 has 240 divisors, whose sum is σ = 76051661400. Its totient is φ = 5775949824.

The previous prime is 21809594879. The next prime is 21809594881. The reversal of 21809594880 is 8849590812.

It is an interprime number because it is at equal distance from previous prime (21809594879) and next prime (21809594881).

It can be written as a sum of positive squares in 4 ways, for example, as 12713013504 + 9096581376 = 112752^2 + 95376^2 .

It is a tau number, because it is divible by the number of its divisors (240).

It is not an unprimeable number, because it can be changed into a prime (21809594881) 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 23 ways as a sum of consecutive naturals, for example, 3429784 + ... + 3436136.

Almost surely, 2^21809594880 is an apocalyptic number.

21809594880 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 21809594880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38025830700).

21809594880 is an abundant number, since it is smaller than the sum of its proper divisors (54242066520).

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

21809594880 is a wasteful number, since it uses less digits than its factorization.

21809594880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6531 (or 6512 counting only the distinct ones).

The product of its (nonzero) digits is 1658880, while the sum is 54.

The spelling of 21809594880 in words is "twenty-one billion, eight hundred nine million, five hundred ninety-four thousand, eight hundred eighty".