21135073 has 2 divisors, whose sum is σ = 21135074. Its totient is φ = 21135072.

The previous prime is 21135071. The next prime is 21135109. The reversal of 21135073 is 37053112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12909649 + 8225424 = 3593^2 + 2868^2 .

It is a cyclic number.

It is not a de Polignac number, because 21135073 - 2¹ = 21135071 is a prime.

Together with 21135071, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21135071) 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, 10567536 + 10567537.

It is an arithmetic number, because the mean of its divisors is an integer number (10567537).

Almost surely, 2^21135073 is an apocalyptic number.

It is an amenable number.

21135073 is a deficient number, since it is larger than the sum of its proper divisors (1).

21135073 is an equidigital number, since it uses as much as digits as its factorization.

21135073 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 630, while the sum is 22.

The square root of 21135073 is about 4597.2897450563. The cubic root of 21135073 is about 276.4826716499.

Adding to 21135073 its reverse (37053112), we get a palindrome (58188185).

The spelling of 21135073 in words is "twenty-one million, one hundred thirty-five thousand, seventy-three".