21901612208 has 80 divisors (see below), whose sum is σ = 51314334720. Its totient is φ = 8846143488.

The previous prime is 21901612177. The next prime is 21901612211. The reversal of 21901612208 is 80221610912.

It is a super-2 number, since 2×21901612208² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 384041 + ... + 437367.

It is an arithmetic number, because the mean of its divisors is an integer number (641429184).

Almost surely, 2^21901612208 is an apocalyptic number.

21901612208 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 21901612208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25657167360).

21901612208 is an abundant number, since it is smaller than the sum of its proper divisors (29412722512).

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

21901612208 is a wasteful number, since it uses less digits than its factorization.

21901612208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53554 (or 53548 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 32.

The spelling of 21901612208 in words is "twenty-one billion, nine hundred one million, six hundred twelve thousand, two hundred eight".