21020002123213 has 4 divisors (see below), whose sum is σ = 21020014256220. Its totient is φ = 21019989990208.

The previous prime is 21020002123187. The next prime is 21020002123223. The reversal of 21020002123213 is 31232120002012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12614977787049 + 8405024336164 = 3551757^2 + 2899142^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21020002123213 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020002123223) 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, 2925820 + ... + 7113397.

It is an arithmetic number, because the mean of its divisors is an integer number (5255003564055).

Almost surely, 2^{21020002123213} is an apocalyptic number.

It is an amenable number.

21020002123213 is a deficient number, since it is larger than the sum of its proper divisors (12133007).

21020002123213 is a wasteful number, since it uses less digits than its factorization.

21020002123213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12133006.

The product of its (nonzero) digits is 288, while the sum is 19.

Adding to 21020002123213 its reverse (31232120002012), we get a palindrome (52252122125225).

The spelling of 21020002123213 in words is "twenty-one trillion, twenty billion, two million, one hundred twenty-three thousand, two hundred thirteen".