21206135 has 8 divisors (see below), whose sum is σ = 25796400. Its totient is φ = 16732224.

The previous prime is 21206131. The next prime is 21206173. The reversal of 21206135 is 53160212.

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

It is a cyclic number.

It is not a de Polignac number, because 21206135 - 2² = 21206131 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21206131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28685 + ... + 29414.

It is an arithmetic number, because the mean of its divisors is an integer number (3224550).

Almost surely, 2^21206135 is an apocalyptic number.

21206135 is a deficient number, since it is larger than the sum of its proper divisors (4590265).

21206135 is an equidigital number, since it uses as much as digits as its factorization.

21206135 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58177.

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

The square root of 21206135 is about 4605.0119435241. The cubic root of 21206135 is about 276.7921955809.

Adding to 21206135 its reverse (53160212), we get a palindrome (74366347).

The spelling of 21206135 in words is "twenty-one million, two hundred six thousand, one hundred thirty-five".