21320203123 has 2 divisors, whose sum is σ = 21320203124. Its totient is φ = 21320203122.

The previous prime is 21320203109. The next prime is 21320203127. The reversal of 21320203123 is 32130202312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21320203123 - 2¹⁷ = 21320072051 is a prime.

It is a super-2 number, since 2×21320203123² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21320203123.

It is not a weakly prime, because it can be changed into another prime (21320203127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660101561 + 10660101562.

It is an arithmetic number, because the mean of its divisors is an integer number (10660101562).

Almost surely, 2^21320203123 is an apocalyptic number.

21320203123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21320203123 is an equidigital number, since it uses as much as digits as its factorization.

21320203123 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 19.

Adding to 21320203123 its reverse (32130202312), we get a palindrome (53450405435).

The spelling of 21320203123 in words is "twenty-one billion, three hundred twenty million, two hundred three thousand, one hundred twenty-three".