21635313728 has 112 divisors (see below), whose sum is σ = 50274931200. Its totient is φ = 9045098496.

The previous prime is 21635313701. The next prime is 21635313769. The reversal of 21635313728 is 82731353612.

It is a tau number, because it is divible by the number of its divisors (112).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7094348 + ... + 7097396.

Almost surely, 2^21635313728 is an apocalyptic number.

21635313728 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 21635313728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25137465600).

21635313728 is an abundant number, since it is smaller than the sum of its proper divisors (28639617472).

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

21635313728 is a wasteful number, since it uses less digits than its factorization.

21635313728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3452 (or 3442 counting only the distinct ones).

The product of its digits is 181440, while the sum is 41.

The spelling of 21635313728 in words is "twenty-one billion, six hundred thirty-five million, three hundred thirteen thousand, seven hundred twenty-eight".