21396065 has 4 divisors (see below), whose sum is σ = 25675284. Its totient is φ = 17116848.

The previous prime is 21396059. The next prime is 21396083. The reversal of 21396065 is 56069312.

It is a happy number.

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 16418704 + 4977361 = 4052^2 + 2231^2 .

It is a cyclic number.

It is not a de Polignac number, because 21396065 - 2¹⁴ = 21379681 is a prime.

It is a Duffinian 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, 2139602 + ... + 2139611.

It is an arithmetic number, because the mean of its divisors is an integer number (6418821).

Almost surely, 2^21396065 is an apocalyptic number.

It is an amenable number.

21396065 is a deficient number, since it is larger than the sum of its proper divisors (4279219).

21396065 is an equidigital number, since it uses as much as digits as its factorization.

21396065 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4279218.

The product of its (nonzero) digits is 9720, while the sum is 32.

The square root of 21396065 is about 4625.5880707214. The cubic root of 21396065 is about 277.6160918911.

The spelling of 21396065 in words is "twenty-one million, three hundred ninety-six thousand, sixty-five".