21003121123 has 2 divisors, whose sum is σ = 21003121124. Its totient is φ = 21003121122.

The previous prime is 21003121081. The next prime is 21003121141. The reversal of 21003121123 is 32112130012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21003121123 - 2²¹ = 21001023971 is a prime.

It is a super-2 number, since 2×21003121123² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21003121097 and 21003121106.

It is not a weakly prime, because it can be changed into another prime (21003121723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501560561 + 10501560562.

It is an arithmetic number, because the mean of its divisors is an integer number (10501560562).

Almost surely, 2^21003121123 is an apocalyptic number.

21003121123 is a deficient number, since it is larger than the sum of its proper divisors (1).

21003121123 is an equidigital number, since it uses as much as digits as its factorization.

21003121123 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 21003121123 its reverse (32112130012), we get a palindrome (53115251135).

The spelling of 21003121123 in words is "twenty-one billion, three million, one hundred twenty-one thousand, one hundred twenty-three".