21002123121131 has 4 divisors (see below), whose sum is σ = 21002134901592. Its totient is φ = 21002111340672.

The previous prime is 21002123121101. The next prime is 21002123121149. The reversal of 21002123121131 is 13112132120012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21002123121131 - 2¹⁸ = 21002122858987 is a prime.

It is a super-2 number, since 2×21002123121131² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21002123121101) 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, 2605430 + ... + 6985163.

It is an arithmetic number, because the mean of its divisors is an integer number (5250533725398).

Almost surely, 2^{21002123121131} is an apocalyptic number.

21002123121131 is a deficient number, since it is larger than the sum of its proper divisors (11780461).

21002123121131 is an equidigital number, since it uses as much as digits as its factorization.

21002123121131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11780460.

The product of its (nonzero) digits is 144, while the sum is 20.

Adding to 21002123121131 its reverse (13112132120012), we get a palindrome (34114255241143).

The spelling of 21002123121131 in words is "twenty-one trillion, two billion, one hundred twenty-three million, one hundred twenty-one thousand, one hundred thirty-one".