21136205 has 8 divisors (see below), whose sum is σ = 25390104. Its totient is φ = 16891200.

The previous prime is 21136187. The next prime is 21136207. The reversal of 21136205 is 50263112.

It can be written as a sum of positive squares in 4 ways, for example, as 6405961 + 14730244 = 2531^2 + 3838^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21136205 - 2²⁴ = 4358989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21136207) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5375 + ... + 8435.

It is an arithmetic number, because the mean of its divisors is an integer number (3173763).

Almost surely, 2^21136205 is an apocalyptic number.

It is an amenable number.

21136205 is a deficient number, since it is larger than the sum of its proper divisors (4253899).

21136205 is a wasteful number, since it uses less digits than its factorization.

21136205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4447.

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

The square root of 21136205 is about 4597.4128594243. The cubic root of 21136205 is about 276.4876077230.

Adding to 21136205 its reverse (50263112), we get a palindrome (71399317).

The spelling of 21136205 in words is "twenty-one million, one hundred thirty-six thousand, two hundred five".