21010945 has 8 divisors (see below), whose sum is σ = 25344936. Its totient is φ = 16720896.

The previous prime is 21010943. The next prime is 21010967. The reversal of 21010945 is 54901012.

It can be written as a sum of positive squares in 4 ways, for example, as 7056 + 21003889 = 84^2 + 4583^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21010945 - 2¹ = 21010943 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21010943) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9922 + ... + 11851.

It is an arithmetic number, because the mean of its divisors is an integer number (3168117).

Almost surely, 2^21010945 is an apocalyptic number.

It is an amenable number.

21010945 is a deficient number, since it is larger than the sum of its proper divisors (4333991).

21010945 is a wasteful number, since it uses less digits than its factorization.

21010945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21971.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 21010945 is about 4583.7697367996. The cubic root of 21010945 is about 275.9403401470.

Adding to 21010945 its reverse (54901012), we get a palindrome (75911957).

The spelling of 21010945 in words is "twenty-one million, ten thousand, nine hundred forty-five".