21015011 has 2 divisors, whose sum is σ = 21015012. Its totient is φ = 21015010.

The previous prime is 21014999. The next prime is 21015013. The reversal of 21015011 is 11051012.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21015011 - 2¹⁰ = 21013987 is a prime.

Together with 21015013, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21014983 and 21015001.

It is not a weakly prime, because it can be changed into another prime (21015013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10507505 + 10507506.

It is an arithmetic number, because the mean of its divisors is an integer number (10507506).

Almost surely, 2^21015011 is an apocalyptic number.

21015011 is a deficient number, since it is larger than the sum of its proper divisors (1).

21015011 is an equidigital number, since it uses as much as digits as its factorization.

21015011 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10, while the sum is 11.

The square root of 21015011 is about 4584.2132367507. The cubic root of 21015011 is about 275.9581388238.

Adding to 21015011 its reverse (11051012), we get a palindrome (32066023).

The spelling of 21015011 in words is "twenty-one million, fifteen thousand, eleven".