21351073 has 2 divisors, whose sum is σ = 21351074. Its totient is φ = 21351072.

The previous prime is 21351053. The next prime is 21351131. The reversal of 21351073 is 37015312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16257024 + 5094049 = 4032^2 + 2257^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21351073 is a prime.

It is not a weakly prime, because it can be changed into another prime (21351013) 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, 10675536 + 10675537.

It is an arithmetic number, because the mean of its divisors is an integer number (10675537).

Almost surely, 2^21351073 is an apocalyptic number.

It is an amenable number.

21351073 is a deficient number, since it is larger than the sum of its proper divisors (1).

21351073 is an equidigital number, since it uses as much as digits as its factorization.

21351073 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 21351073 is about 4620.7221297109. The cubic root of 21351073 is about 277.4213634285.

Adding to 21351073 its reverse (37015312), we get a palindrome (58366385).

The spelling of 21351073 in words is "twenty-one million, three hundred fifty-one thousand, seventy-three".