21130321 has 2 divisors, whose sum is σ = 21130322. Its totient is φ = 21130320.

The previous prime is 21130301. The next prime is 21130331. The reversal of 21130321 is 12303112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20575296 + 555025 = 4536^2 + 745^2 .

It is a cyclic number.

It is not a de Polignac number, because 21130321 - 2⁹ = 21129809 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21130301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10565160 + 10565161.

It is an arithmetic number, because the mean of its divisors is an integer number (10565161).

Almost surely, 2^21130321 is an apocalyptic number.

It is an amenable number.

21130321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21130321 is an equidigital number, since it uses as much as digits as its factorization.

21130321 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 21130321 is about 4596.7728897565. The cubic root of 21130321 is about 276.4619486848.

Adding to 21130321 its reverse (12303112), we get a palindrome (33433433).

The spelling of 21130321 in words is "twenty-one million, one hundred thirty thousand, three hundred twenty-one".