21012120121001 has 4 divisors (see below), whose sum is σ = 21265278194832. Its totient is φ = 20758962047172.

The previous prime is 21012120120967. The next prime is 21012120121021. The reversal of 21012120121001 is 10012102121012.

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-21012120121001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21012120121021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 126579036791 + ... + 126579036956.

It is an arithmetic number, because the mean of its divisors is an integer number (5316319548708).

Almost surely, 2^{21012120121001} is an apocalyptic number.

It is an amenable number.

21012120121001 is a deficient number, since it is larger than the sum of its proper divisors (253158073831).

21012120121001 is an equidigital number, since it uses as much as digits as its factorization.

21012120121001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 253158073830.

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

Adding to 21012120121001 its reverse (10012102121012), we get a palindrome (31024222242013).

The spelling of 21012120121001 in words is "twenty-one trillion, twelve billion, one hundred twenty million, one hundred twenty-one thousand, one".