21320311 has 2 divisors, whose sum is σ = 21320312. Its totient is φ = 21320310.

The previous prime is 21320297. The next prime is 21320317. The reversal of 21320311 is 11302312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21320311 - 2⁷ = 21320183 is a prime.

It is a super-2 number, since 2×21320311² = 909111322273442, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21320291 and 21320300.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21320317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10660155 + 10660156.

It is an arithmetic number, because the mean of its divisors is an integer number (10660156).

Almost surely, 2^21320311 is an apocalyptic number.

21320311 is a deficient number, since it is larger than the sum of its proper divisors (1).

21320311 is an equidigital number, since it uses as much as digits as its factorization.

21320311 is an odious number, because the sum of its binary digits is odd.

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

The square root of 21320311 is about 4617.3922293866. The cubic root of 21320311 is about 277.2880658686.

Adding to 21320311 its reverse (11302312), we get a palindrome (32622623).

The spelling of 21320311 in words is "twenty-one million, three hundred twenty thousand, three hundred eleven".