21201021000 has 384 divisors, whose sum is σ = 76079203200. Its totient is φ = 5519404800.

The previous prime is 21201020927. The next prime is 21201021007. The reversal of 21201021000 is 12010212.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is not an unprimeable number, because it can be changed into a prime (21201021007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 10447986 + ... + 10450014.

It is an arithmetic number, because the mean of its divisors is an integer number (198122925).

Almost surely, 2^21201021000 is an apocalyptic number.

21201021000 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 21201021000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38039601600).

21201021000 is an abundant number, since it is smaller than the sum of its proper divisors (54878182200).

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

21201021000 is a wasteful number, since it uses less digits than its factorization.

21201021000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2108 (or 2082 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 21201021000 its reverse (12010212), we get a palindrome (21213031212).

The spelling of 21201021000 in words is "twenty-one billion, two hundred one million, twenty-one thousand".