21027811 has 6 divisors (see below), whose sum is σ = 24460980. Its totient is φ = 18023796.

The previous prime is 21027791. The next prime is 21027833. The reversal of 21027811 is 11872012.

It is not a de Polignac number, because 21027811 - 2⁷ = 21027683 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21027841) 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 in 5 ways as a sum of consecutive naturals, for example, 214521 + ... + 214618.

It is an arithmetic number, because the mean of its divisors is an integer number (4076830).

Almost surely, 2^21027811 is an apocalyptic number.

21027811 is a deficient number, since it is larger than the sum of its proper divisors (3433169).

21027811 is an equidigital number, since it uses as much as digits as its factorization.

21027811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 429153 (or 429146 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 22.

The square root of 21027811 is about 4585.6091198444. The cubic root of 21027811 is about 276.0141550886.

Adding to 21027811 its reverse (11872012), we get a palindrome (32899823).

The spelling of 21027811 in words is "twenty-one million, twenty-seven thousand, eight hundred eleven".