21243220208 has 60 divisors (see below), whose sum is σ = 48605125680. Its totient is φ = 8810507520.

The previous prime is 21243220183. The next prime is 21243220217. The reversal of 21243220208 is 80202234212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8948 + ... + 206316.

It is an arithmetic number, because the mean of its divisors is an integer number (810085428).

Almost surely, 2^21243220208 is an apocalyptic number.

21243220208 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 21243220208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24302562840).

21243220208 is an abundant number, since it is smaller than the sum of its proper divisors (27361905472).

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

21243220208 is a wasteful number, since it uses less digits than its factorization.

21243220208 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 197446 (or 197409 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 26.

The spelling of 21243220208 in words is "twenty-one billion, two hundred forty-three million, two hundred twenty thousand, two hundred eight".