21027730 has 16 divisors (see below), whose sum is σ = 37995480. Its totient is φ = 8378752.

The previous prime is 21027709. The next prime is 21027767. The reversal of 21027730 is 3772012.

It can be written as a sum of positive squares in 4 ways, for example, as 4405801 + 16621929 = 2099^2 + 4077^2 .

It is an unprimeable number.

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, 1219 + ... + 6598.

Almost surely, 2^21027730 is an apocalyptic number.

21027730 is a deficient number, since it is larger than the sum of its proper divisors (16967750).

21027730 is a wasteful number, since it uses less digits than its factorization.

21027730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8093.

The product of its (nonzero) digits is 588, while the sum is 22.

The square root of 21027730 is about 4585.6002878576. The cubic root of 21027730 is about 276.0138006822.

Adding to 21027730 its reverse (3772012), we get a palindrome (24799742).

The spelling of 21027730 in words is "twenty-one million, twenty-seven thousand, seven hundred thirty".