21102001000 has 64 divisors (see below), whose sum is σ = 49433042880. Its totient is φ = 8431508800.

The previous prime is 21102000937. The next prime is 21102001007. The reversal of 21102001000 is 10020112.

It is not an unprimeable number, because it can be changed into a prime (21102001007) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 935859 + ... + 958141.

It is an arithmetic number, because the mean of its divisors is an integer number (772391295).

Almost surely, 2^21102001000 is an apocalyptic number.

21102001000 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 21102001000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24716521440).

21102001000 is an abundant number, since it is smaller than the sum of its proper divisors (28331041880).

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

21102001000 is a wasteful number, since it uses less digits than its factorization.

21102001000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23251 (or 23237 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 7.

Adding to 21102001000 its reverse (10020112), we get a palindrome (21112021112).

The spelling of 21102001000 in words is "twenty-one billion, one hundred two million, one thousand".