21205363 has 4 divisors (see below), whose sum is σ = 21367368. Its totient is φ = 21043360.

The previous prime is 21205361. The next prime is 21205381. The reversal of 21205363 is 36350212.

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

It is a cyclic number.

It is not a de Polignac number, because 21205363 - 2¹ = 21205361 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21205361) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 80806 + ... + 81067.

It is an arithmetic number, because the mean of its divisors is an integer number (5341842).

Almost surely, 2^21205363 is an apocalyptic number.

21205363 is a deficient number, since it is larger than the sum of its proper divisors (162005).

21205363 is a wasteful number, since it uses less digits than its factorization.

21205363 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 162004.

The product of its (nonzero) digits is 1080, while the sum is 22.

The square root of 21205363 is about 4604.9281210460. The cubic root of 21205363 is about 276.7888367075.

Adding to 21205363 its reverse (36350212), we get a palindrome (57555575).

The spelling of 21205363 in words is "twenty-one million, two hundred five thousand, three hundred sixty-three".