21203123107 has 2 divisors, whose sum is σ = 21203123108. Its totient is φ = 21203123106.

The previous prime is 21203123099. The next prime is 21203123119. The reversal of 21203123107 is 70132130212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21203123107 - 2³ = 21203123099 is a prime.

It is not a weakly prime, because it can be changed into another prime (21203103107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601561553 + 10601561554.

It is an arithmetic number, because the mean of its divisors is an integer number (10601561554).

Almost surely, 2^21203123107 is an apocalyptic number.

21203123107 is a deficient number, since it is larger than the sum of its proper divisors (1).

21203123107 is an equidigital number, since it uses as much as digits as its factorization.

21203123107 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 504, while the sum is 22.

Adding to 21203123107 its reverse (70132130212), we get a palindrome (91335253319).

The spelling of 21203123107 in words is "twenty-one billion, two hundred three million, one hundred twenty-three thousand, one hundred seven".