21111020321 has 2 divisors, whose sum is σ = 21111020322. Its totient is φ = 21111020320.

The previous prime is 21111020317. The next prime is 21111020353. The reversal of 21111020321 is 12302011112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10622188096 + 10488832225 = 103064^2 + 102415^2 .

It is a cyclic number.

It is not a de Polignac number, because 21111020321 - 2² = 21111020317 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21111020296 and 21111020305.

It is not a weakly prime, because it can be changed into another prime (21111020311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555510160 + 10555510161.

It is an arithmetic number, because the mean of its divisors is an integer number (10555510161).

Almost surely, 2^21111020321 is an apocalyptic number.

It is an amenable number.

21111020321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111020321 is an equidigital number, since it uses as much as digits as its factorization.

21111020321 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 24, while the sum is 14.

Adding to 21111020321 its reverse (12302011112), we get a palindrome (33413031433).

The spelling of 21111020321 in words is "twenty-one billion, one hundred eleven million, twenty thousand, three hundred twenty-one".