21808203648 has 384 divisors, whose sum is σ = 76620768000. Its totient is φ = 5364817920.

The previous prime is 21808203631. The next prime is 21808203649. The reversal of 21808203648 is 84630280812.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21808203649) 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 47 ways as a sum of consecutive naturals, for example, 6177948 + ... + 6181476.

It is an arithmetic number, because the mean of its divisors is an integer number (199533250).

Almost surely, 2^21808203648 is an apocalyptic number.

21808203648 is a gapful number since it is divisible by the number (28) 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 21808203648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38310384000).

21808203648 is an abundant number, since it is smaller than the sum of its proper divisors (54812564352).

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

21808203648 is a wasteful number, since it uses less digits than its factorization.

21808203648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3594 (or 3571 counting only the distinct ones).

The product of its (nonzero) digits is 147456, while the sum is 42.

It can be divided in two parts, 21808 and 203648, that added together give a triangular number (225456 = T₆₇₁).

The spelling of 21808203648 in words is "twenty-one billion, eight hundred eight million, two hundred three thousand, six hundred forty-eight".