21203123213 has 4 divisors (see below), whose sum is σ = 21413055228. Its totient is φ = 20993191200.

The previous prime is 21203123159. The next prime is 21203123233. The reversal of 21203123213 is 31232130212.

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 19488997609 + 1714125604 = 139603^2 + 41402^2 .

It is a cyclic number.

It is not a de Polignac number, because 21203123213 - 2¹⁶ = 21203057677 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 (21203123233) 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, 104965856 + ... + 104966057.

It is an arithmetic number, because the mean of its divisors is an integer number (5353263807).

Almost surely, 2^21203123213 is an apocalyptic number.

It is an amenable number.

21203123213 is a deficient number, since it is larger than the sum of its proper divisors (209932015).

21203123213 is a wasteful number, since it uses less digits than its factorization.

21203123213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 209932014.

The product of its (nonzero) digits is 432, while the sum is 20.

Adding to 21203123213 its reverse (31232130212), we get a palindrome (52435253425).

The spelling of 21203123213 in words is "twenty-one billion, two hundred three million, one hundred twenty-three thousand, two hundred thirteen".