21051311 has 2 divisors, whose sum is σ = 21051312. Its totient is φ = 21051310.

The previous prime is 21051271. The next prime is 21051323. The reversal of 21051311 is 11315012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21051311 - 2¹⁰ = 21050287 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21051341) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10525655 + 10525656.

It is an arithmetic number, because the mean of its divisors is an integer number (10525656).

Almost surely, 2^21051311 is an apocalyptic number.

21051311 is a deficient number, since it is larger than the sum of its proper divisors (1).

21051311 is an equidigital number, since it uses as much as digits as its factorization.

21051311 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 30, while the sum is 14.

The square root of 21051311 is about 4588.1707684000. The cubic root of 21051311 is about 276.1169383002.

Adding to 21051311 its reverse (11315012), we get a palindrome (32366323).

The spelling of 21051311 in words is "twenty-one million, fifty-one thousand, three hundred eleven".