21011121000 has 192 divisors, whose sum is σ = 74106040320. Its totient is φ = 5359305600.

The previous prime is 21011120993. The next prime is 21011121011. The reversal of 21011121000 is 12111012.

It is a happy number.

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

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 156249 + ... + 257751.

It is an arithmetic number, because the mean of its divisors is an integer number (385968960).

Almost surely, 2^21011121000 is an apocalyptic number.

21011121000 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 21011121000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37053020160).

21011121000 is an abundant number, since it is smaller than the sum of its proper divisors (53094919320).

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

21011121000 is a wasteful number, since it uses less digits than its factorization.

21011121000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 101553 (or 101536 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21011121000 its reverse (12111012), we get a palindrome (21023232012).

The spelling of 21011121000 in words is "twenty-one billion, eleven million, one hundred twenty-one thousand".