21163205 has 16 divisors (see below), whose sum is σ = 29286144. Its totient is φ = 14380800.

The previous prime is 21163201. The next prime is 21163229. The reversal of 21163205 is 50236112.

It is not a de Polignac number, because 21163205 - 2² = 21163201 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21163201) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1280 + ... + 6630.

It is an arithmetic number, because the mean of its divisors is an integer number (1830384).

Almost surely, 2^21163205 is an apocalyptic number.

It is an amenable number.

21163205 is a deficient number, since it is larger than the sum of its proper divisors (8122939).

21163205 is a wasteful number, since it uses less digits than its factorization.

21163205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5476.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 21163205 is about 4600.3483563748. The cubic root of 21163205 is about 276.6052887183.

Adding to 21163205 its reverse (50236112), we get a palindrome (71399317).

The spelling of 21163205 in words is "twenty-one million, one hundred sixty-three thousand, two hundred five".