21021000000 has 1176 divisors, whose sum is σ = 95010658848. Its totient is φ = 4032000000.

The previous prime is 21020999981. The next prime is 21021000017. The reversal of 21021000000 is 12012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (1176).

It is a Harshad number since it is a multiple of its sum of digits (6).

It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 167 ways as a sum of consecutive naturals, for example, 1616999994 + ... + 1617000006.

Almost surely, 2^21021000000 is an apocalyptic number.

21021000000 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 21021000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47505329424).

21021000000 is an abundant number, since it is smaller than the sum of its proper divisors (73989658848).

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

21021000000 is an equidigital number, since it uses as much as digits as its factorization.

21021000000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83 (or 41 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 6.

Adding to 21021000000 its reverse (12012), we get a palindrome (21021012012).

The spelling of 21021000000 in words is "twenty-one billion, twenty-one million", and thus it is an aban number and an uban number.