21315211 has 2 divisors, whose sum is σ = 21315212. Its totient is φ = 21315210.

The previous prime is 21315187. The next prime is 21315221. The reversal of 21315211 is 11251312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21315211 - 2⁷ = 21315083 is a prime.

It is not a weakly prime, because it can be changed into another prime (21315221) 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, 10657605 + 10657606.

It is an arithmetic number, because the mean of its divisors is an integer number (10657606).

Almost surely, 2^21315211 is an apocalyptic number.

21315211 is a deficient number, since it is larger than the sum of its proper divisors (1).

21315211 is an equidigital number, since it uses as much as digits as its factorization.

21315211 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 60, while the sum is 16.

The square root of 21315211 is about 4616.8399365800. The cubic root of 21315211 is about 277.2659542163.

Adding to 21315211 its reverse (11251312), we get a palindrome (32566523).

The spelling of 21315211 in words is "twenty-one million, three hundred fifteen thousand, two hundred eleven".