21102002321 has 2 divisors, whose sum is σ = 21102002322. Its totient is φ = 21102002320.

The previous prime is 21102002293. The next prime is 21102002323. The reversal of 21102002321 is 12320020112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16890641296 + 4211361025 = 129964^2 + 64895^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21102002321 is a prime.

It is a Sophie Germain prime.

Together with 21102002323, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21102002296 and 21102002305.

It is not a weakly prime, because it can be changed into another prime (21102002323) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10551001160 + 10551001161.

It is an arithmetic number, because the mean of its divisors is an integer number (10551001161).

Almost surely, 2^21102002321 is an apocalyptic number.

It is an amenable number.

21102002321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21102002321 is an equidigital number, since it uses as much as digits as its factorization.

21102002321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 48, while the sum is 14.

Adding to 21102002321 its reverse (12320020112), we get a palindrome (33422022433).

The spelling of 21102002321 in words is "twenty-one billion, one hundred two million, two thousand, three hundred twenty-one".