21240211 has 2 divisors, whose sum is σ = 21240212. Its totient is φ = 21240210.

The previous prime is 21240179. The next prime is 21240221. The reversal of 21240211 is 11204212.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21240211 - 2⁵ = 21240179 is a prime.

It is a super-2 number, since 2×21240211² = 902293126649042, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21240191 and 21240200.

It is not a weakly prime, because it can be changed into another prime (21240221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10620105 + 10620106.

It is an arithmetic number, because the mean of its divisors is an integer number (10620106).

Almost surely, 2^21240211 is an apocalyptic number.

21240211 is a deficient number, since it is larger than the sum of its proper divisors (1).

21240211 is an equidigital number, since it uses as much as digits as its factorization.

21240211 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 21240211 is about 4608.7103402145. The cubic root of 21240211 is about 276.9403747643.

Adding to 21240211 its reverse (11204212), we get a palindrome (32444423).

The spelling of 21240211 in words is "twenty-one million, two hundred forty thousand, two hundred eleven".