21135611 has 6 divisors (see below), whose sum is σ = 24586380. Its totient is φ = 18116196.

The previous prime is 21135593. The next prime is 21135613. The reversal of 21135611 is 11653112.

It is a de Polignac number, because none of the positive numbers 2^k-21135611 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21135613) 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 5 ways as a sum of consecutive naturals, for example, 215621 + ... + 215718.

It is an arithmetic number, because the mean of its divisors is an integer number (4097730).

Almost surely, 2^21135611 is an apocalyptic number.

21135611 is a deficient number, since it is larger than the sum of its proper divisors (3450769).

21135611 is an equidigital number, since it uses as much as digits as its factorization.

21135611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 431353 (or 431346 counting only the distinct ones).

The product of its digits is 180, while the sum is 20.

The square root of 21135611 is about 4597.3482574197. The cubic root of 21135611 is about 276.4850176147.

Adding to 21135611 its reverse (11653112), we get a palindrome (32788723).

The spelling of 21135611 in words is "twenty-one million, one hundred thirty-five thousand, six hundred eleven".