21012002221121 has 4 divisors (see below), whose sum is σ = 21091895765952. Its totient is φ = 20932108676292.

The previous prime is 21012002221099. The next prime is 21012002221123. The reversal of 21012002221121 is 12112220021012.

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 not a de Polignac number, because 21012002221121 - 2¹⁸ = 21012001958977 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21012002221121.

It is not an unprimeable number, because it can be changed into a prime (21012002221123) 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, 39946772021 + ... + 39946772546.

It is an arithmetic number, because the mean of its divisors is an integer number (5272973941488).

Almost surely, 2^{21012002221121} is an apocalyptic number.

It is an amenable number.

21012002221121 is a deficient number, since it is larger than the sum of its proper divisors (79893544831).

21012002221121 is an equidigital number, since it uses as much as digits as its factorization.

21012002221121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79893544830.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21012002221121 its reverse (12112220021012), we get a palindrome (33124222242133).

The spelling of 21012002221121 in words is "twenty-one trillion, twelve billion, two million, two hundred twenty-one thousand, one hundred twenty-one".