21270206 has 4 divisors (see below), whose sum is σ = 31905312. Its totient is φ = 10635102.

The previous prime is 21270191. The next prime is 21270217. The reversal of 21270206 is 60207212.

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

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 5317550 + ... + 5317553.

It is an arithmetic number, because the mean of its divisors is an integer number (7976328).

Almost surely, 2^21270206 is an apocalyptic number.

21270206 is a deficient number, since it is larger than the sum of its proper divisors (10635106).

21270206 is a wasteful number, since it uses less digits than its factorization.

21270206 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10635105.

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 21270206 is about 4611.9633563158. The cubic root of 21270206 is about 277.0706766613.

Adding to 21270206 its reverse (60207212), we get a palindrome (81477418).

The spelling of 21270206 in words is "twenty-one million, two hundred seventy thousand, two hundred six".