21010810 has 16 divisors (see below), whose sum is σ = 40044456. Its totient is φ = 7909888.

The previous prime is 21010763. The next prime is 21010811. The reversal of 21010810 is 1801012.

It can be written as a sum of positive squares in 4 ways, for example, as 18258529 + 2752281 = 4273^2 + 1659^2 .

It is a super-2 number, since 2×21010810² = 882908273712200, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21010811) 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 in 7 ways as a sum of consecutive naturals, for example, 61627 + ... + 61966.

Almost surely, 2^21010810 is an apocalyptic number.

21010810 is a deficient number, since it is larger than the sum of its proper divisors (19033646).

21010810 is a wasteful number, since it uses less digits than its factorization.

21010810 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123617.

The product of its (nonzero) digits is 16, while the sum is 13.

The square root of 21010810 is about 4583.7550109054. The cubic root of 21010810 is about 275.9397491530.

Adding to 21010810 its reverse (1801012), we get a palindrome (22811822).

The spelling of 21010810 in words is "twenty-one million, ten thousand, eight hundred ten".