21136215 has 16 divisors (see below), whose sum is σ = 34984800. Its totient is φ = 10883712.

The previous prime is 21136211. The next prime is 21136217. The reversal of 21136215 is 51263112.

It is not a de Polignac number, because 21136215 - 2² = 21136211 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21136191 and 21136200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21136211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23860 + ... + 24729.

It is an arithmetic number, because the mean of its divisors is an integer number (2186550).

Almost surely, 2^21136215 is an apocalyptic number.

21136215 is a deficient number, since it is larger than the sum of its proper divisors (13848585).

21136215 is a wasteful number, since it uses less digits than its factorization.

21136215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48626.

The product of its digits is 360, while the sum is 21.

The square root of 21136215 is about 4597.4139469924. The cubic root of 21136215 is about 276.4876513271.

Adding to 21136215 its reverse (51263112), we get a palindrome (72399327).

The spelling of 21136215 in words is "twenty-one million, one hundred thirty-six thousand, two hundred fifteen".