21535040000 has 200 divisors, whose sum is σ = 54217629180. Its totient is φ = 8542208000.

The previous prime is 21535039963. The next prime is 21535040017. The reversal of 21535040000 is 4053512.

It can be written as a sum of positive squares in 10 ways, for example, as 711395584 + 20823644416 = 26672^2 + 144304^2 .

It is a tau number, because it is divible by the number of its divisors (200).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 55359806 + ... + 55360194.

Almost surely, 2^21535040000 is an apocalyptic number.

21535040000 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 21535040000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27108814590).

21535040000 is an abundant number, since it is smaller than the sum of its proper divisors (32682589180).

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

21535040000 is an frugal number, since it uses more digits than its factorization.

21535040000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 600 (or 569 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 20.

Adding to 21535040000 its reverse (4053512), we get a palindrome (21539093512).

The spelling of 21535040000 in words is "twenty-one billion, five hundred thirty-five million, forty thousand".