21033123121 has 2 divisors, whose sum is σ = 21033123122. Its totient is φ = 21033123120.

The previous prime is 21033123107. The next prime is 21033123127. The reversal of 21033123121 is 12132133012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20724769521 + 308353600 = 143961^2 + 17560^2 .

It is a cyclic number.

It is not a de Polignac number, because 21033123121 - 2¹³ = 21033114929 is a prime.

It is not a weakly prime, because it can be changed into another prime (21033123127) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10516561560 + 10516561561.

It is an arithmetic number, because the mean of its divisors is an integer number (10516561561).

Almost surely, 2^21033123121 is an apocalyptic number.

It is an amenable number.

21033123121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21033123121 is an equidigital number, since it uses as much as digits as its factorization.

21033123121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 216, while the sum is 19.

Adding to 21033123121 its reverse (12132133012), we get a palindrome (33165256133).

The spelling of 21033123121 in words is "twenty-one billion, thirty-three million, one hundred twenty-three thousand, one hundred twenty-one".