21028398336 has 810 divisors, whose sum is σ = 75738646830. Its totient is φ = 5790597120.

The previous prime is 21028398311. The next prime is 21028398337. The reversal of 21028398336 is 63389382012.

It can be written as a sum of positive squares in 3 ways, for example, as 8734023936 + 12294374400 = 93456^2 + 110880^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21028398291 and 21028398300.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21028398337) by changing a digit.

It is a polite number, since it can be written in 89 ways as a sum of consecutive naturals, for example, 725117170 + ... + 725117198.

Almost surely, 2^21028398336 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21028398336, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37869323415).

21028398336 is an abundant number, since it is smaller than the sum of its proper divisors (54710248494).

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

21028398336 is a wasteful number, since it uses less digits than its factorization.

21028398336 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113 (or 62 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 45.

The spelling of 21028398336 in words is "twenty-one billion, twenty-eight million, three hundred ninety-eight thousand, three hundred thirty-six".