21027805 has 8 divisors (see below), whose sum is σ = 25385472. Its totient is φ = 16720848.

The previous prime is 21027791. The next prime is 21027833. The reversal of 21027805 is 50872012.

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 21027805 - 2¹³ = 21019613 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21027805.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11757 + ... + 13426.

It is an arithmetic number, because the mean of its divisors is an integer number (3173184).

Almost surely, 2^21027805 is an apocalyptic number.

It is an amenable number.

21027805 is a deficient number, since it is larger than the sum of its proper divisors (4357667).

21027805 is a wasteful number, since it uses less digits than its factorization.

21027805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25355.

The product of its (nonzero) digits is 1120, while the sum is 25.

The square root of 21027805 is about 4585.6084656237. The cubic root of 21027805 is about 276.0141288363.

Adding to 21027805 its reverse (50872012), we get a palindrome (71899817).

The spelling of 21027805 in words is "twenty-one million, twenty-seven thousand, eight hundred five".