21012311 has 2 divisors, whose sum is σ = 21012312. Its totient is φ = 21012310.

The previous prime is 21012307. The next prime is 21012331. The reversal of 21012311 is 11321012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21012311 - 2² = 21012307 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21012292 and 21012301.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21012301) 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, 10506155 + 10506156.

It is an arithmetic number, because the mean of its divisors is an integer number (10506156).

Almost surely, 2^21012311 is an apocalyptic number.

21012311 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012311 is an equidigital number, since it uses as much as digits as its factorization.

21012311 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 21012311 is about 4583.9187383722. The cubic root of 21012311 is about 275.9463199881.

Adding to 21012311 its reverse (11321012), we get a palindrome (32333323).

It can be divided in two parts, 210 and 12311, that added together give a palindrome (12521).

The spelling of 21012311 in words is "twenty-one million, twelve thousand, three hundred eleven".