21001012002 has 24 divisors (see below), whose sum is σ = 45518364684. Its totient is φ = 6997849344.

The previous prime is 21001011947. The next prime is 21001012007. The reversal of 21001012002 is 20021010012.

It can be written as a sum of positive squares in 2 ways, for example, as 20454434361 + 546577641 = 143019^2 + 23379^2 .

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 (21001012007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 154923 + ... + 256910.

Almost surely, 2^21001012002 is an apocalyptic number.

21001012002 is an abundant number, since it is smaller than the sum of its proper divisors (24517352682).

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

21001012002 is a wasteful number, since it uses less digits than its factorization.

21001012002 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 414674 (or 414671 counting only the distinct ones).

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

Adding to 21001012002 its reverse (20021010012), we get a palindrome (41022022014).

The spelling of 21001012002 in words is "twenty-one billion, one million, twelve thousand, two".