21001212121001 has 4 divisors (see below), whose sum is σ = 24001385281152. Its totient is φ = 18001038960852.

The previous prime is 21001212120871. The next prime is 21001212121031. The reversal of 21001212121001 is 10012121210012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21001212121001 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21001212121031) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1500086580065 + ... + 1500086580078.

It is an arithmetic number, because the mean of its divisors is an integer number (6000346320288).

Almost surely, 2^{21001212121001} is an apocalyptic number.

It is an amenable number.

21001212121001 is a deficient number, since it is larger than the sum of its proper divisors (3000173160151).

21001212121001 is an equidigital number, since it uses as much as digits as its factorization.

21001212121001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3000173160150.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21001212121001 its reverse (10012121210012), we get a palindrome (31013333331013).

It can be divided in two parts, 2 and 1001212121001, that multiplied together give a palindrome (2002424242002).

The spelling of 21001212121001 in words is "twenty-one trillion, one billion, two hundred twelve million, one hundred twenty-one thousand, one".