21028432208 has 160 divisors (see below), whose sum is σ = 49025433600. Its totient is φ = 8548259328.

The previous prime is 21028432207. The next prime is 21028432223. The reversal of 21028432208 is 80223482012.

It is a super-2 number, since 2×21028432208² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21028432207) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 79955885 + ... + 79956147.

It is an arithmetic number, because the mean of its divisors is an integer number (306408960).

Almost surely, 2^21028432208 is an apocalyptic number.

21028432208 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 21028432208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24512716800).

21028432208 is an abundant number, since it is smaller than the sum of its proper divisors (27997001392).

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

21028432208 is a wasteful number, since it uses less digits than its factorization.

21028432208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 649 (or 643 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 32.

The spelling of 21028432208 in words is "twenty-one billion, twenty-eight million, four hundred thirty-two thousand, two hundred eight".