21650065 has 4 divisors (see below), whose sum is σ = 25980084. Its totient is φ = 17320048.

The previous prime is 21650021. The next prime is 21650087. The reversal of 21650065 is 56005612.

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 8661249 + 12988816 = 2943^2 + 3604^2 .

It is a cyclic number.

It is not a de Polignac number, because 21650065 - 2⁹ = 21649553 is a prime.

It is a Duffinian number.

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 3 ways as a sum of consecutive naturals, for example, 2165002 + ... + 2165011.

It is an arithmetic number, because the mean of its divisors is an integer number (6495021).

Almost surely, 2^21650065 is an apocalyptic number.

It is an amenable number.

21650065 is a deficient number, since it is larger than the sum of its proper divisors (4330019).

21650065 is an equidigital number, since it uses as much as digits as its factorization.

21650065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4330018.

The product of its (nonzero) digits is 1800, while the sum is 25.

The square root of 21650065 is about 4652.9630344545. The cubic root of 21650065 is about 278.7103317170.

Adding to 21650065 its reverse (56005612), we get a palindrome (77655677).

The spelling of 21650065 in words is "twenty-one million, six hundred fifty thousand, sixty-five".