21001012001 has 8 divisors (see below), whose sum is σ = 21059212200. Its totient is φ = 20942841600.

The previous prime is 21001011947. The next prime is 21001012007. The reversal of 21001012001 is 10021010012.

It can be written as a sum of positive squares in 4 ways, for example, as 15525160000 + 5475852001 = 124600^2 + 73999^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21001012001 - 2⁶ = 21001011937 is a prime.

It is a super-2 number, since 2×21001012001² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21001012001.

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 7 ways as a sum of consecutive naturals, for example, 2734595 + ... + 2742263.

It is an arithmetic number, because the mean of its divisors is an integer number (2632401525).

Almost surely, 2^21001012001 is an apocalyptic number.

It is an amenable number.

21001012001 is a deficient number, since it is larger than the sum of its proper divisors (58200199).

21001012001 is an equidigital number, since it uses as much as digits as its factorization.

21001012001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14899.

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 21001012001 its reverse (10021010012), we get a palindrome (31022022013).

It can be divided in two parts, 2100 and 1012001, that added together give a palindrome (1014101).

The spelling of 21001012001 in words is "twenty-one billion, one million, twelve thousand, one".