21212001000 has 192 divisors, whose sum is σ = 72369910080. Its totient is φ = 5603414400.

The previous prime is 21212000987. The next prime is 21212001029. The reversal of 21212001000 is 10021212.

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

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 47 ways as a sum of consecutive naturals, for example, 951987 + ... + 974013.

It is an arithmetic number, because the mean of its divisors is an integer number (376926615).

Almost surely, 2^21212001000 is an apocalyptic number.

21212001000 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 21212001000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36184955040).

21212001000 is an abundant number, since it is smaller than the sum of its proper divisors (51157909080).

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

21212001000 is a wasteful number, since it uses less digits than its factorization.

21212001000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22161 (or 22144 counting only the distinct ones).

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

Adding to 21212001000 its reverse (10021212), we get a palindrome (21222022212).

The spelling of 21212001000 in words is "twenty-one billion, two hundred twelve million, one thousand".