21802085 has 4 divisors (see below), whose sum is σ = 26162508. Its totient is φ = 17441664.

The previous prime is 21802051. The next prime is 21802097. The reversal of 21802085 is 58020812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2292196 + 19509889 = 1514^2 + 4417^2 .

It is a cyclic number.

It is not a de Polignac number, because 21802085 - 2¹⁰ = 21801061 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2180204 + ... + 2180213.

It is an arithmetic number, because the mean of its divisors is an integer number (6540627).

Almost surely, 2^21802085 is an apocalyptic number.

It is an amenable number.

21802085 is a deficient number, since it is larger than the sum of its proper divisors (4360423).

21802085 is an equidigital number, since it uses as much as digits as its factorization.

21802085 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4360422.

The product of its (nonzero) digits is 1280, while the sum is 26.

The square root of 21802085 is about 4669.2702856014. The cubic root of 21802085 is about 279.3611497954.

Adding to 21802085 its reverse (58020812), we get a palindrome (79822897).

The spelling of 21802085 in words is "twenty-one million, eight hundred two thousand, eighty-five".