21100012002 has 64 divisors (see below), whose sum is σ = 47871855360. Its totient is φ = 6886444032.

The previous prime is 21100012001. The next prime is 21100012007. The reversal of 21100012002 is 20021000112.

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 (21100012001) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1432258 + ... + 1446914.

It is an arithmetic number, because the mean of its divisors is an integer number (747997740).

Almost surely, 2^21100012002 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21100012002, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23935927680).

21100012002 is an abundant number, since it is smaller than the sum of its proper divisors (26771843358).

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

21100012002 is a wasteful number, since it uses less digits than its factorization.

21100012002 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15224 (or 15218 counting only the distinct ones).

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

Adding to 21100012002 its reverse (20021000112), we get a palindrome (41121012114).

The spelling of 21100012002 in words is "twenty-one billion, one hundred million, twelve thousand, two".