21000122000 has 320 divisors, whose sum is σ = 60329138688. Its totient is φ = 6969600000.

The previous prime is 21000121997. The next prime is 21000122027. The reversal of 21000122000 is 22100012.

It is a Harshad number since it is a multiple of its sum of digits (8).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 28885637 + ... + 28886363.

Almost surely, 2^21000122000 is an apocalyptic number.

21000122000 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 21000122000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30164569344).

21000122000 is an abundant number, since it is smaller than the sum of its proper divisors (39329016688).

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

21000122000 is a wasteful number, since it uses less digits than its factorization.

21000122000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 875 (or 859 counting only the distinct ones).

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

Adding to 21000122000 its reverse (22100012), we get a palindrome (21022222012).

It can be divided in two parts, 2100012 and 2000, that added together give a palindrome (2102012).

The spelling of 21000122000 in words is "twenty-one billion, one hundred twenty-two thousand".