21001600000 has 132 divisors (see below), whose sum is σ = 52483000248. Its totient is φ = 8399360000.

The previous prime is 21001599979. The next prime is 21001600013. The reversal of 21001600000 is 610012.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a self number, because there is not a number n which added to its sum of digits gives 21001600000.

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, 3196719 + ... + 3203281.

Almost surely, 2^21001600000 is an apocalyptic number.

21001600000 is a gapful number since it is divisible by the number (20) 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 21001600000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26241500124).

21001600000 is an abundant number, since it is smaller than the sum of its proper divisors (31481400248).

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

21001600000 is an frugal number, since it uses more digits than its factorization.

21001600000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6608 (or 6570 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 10.

The spelling of 21001600000 in words is "twenty-one billion, one million, six hundred thousand".