21312135 has 48 divisors (see below), whose sum is σ = 42142464. Its totient is φ = 9870336.

The previous prime is 21312121. The next prime is 21312149. The reversal of 21312135 is 53121312.

It is an interprime number because it is at equal distance from previous prime (21312121) and next prime (21312149).

It is not a de Polignac number, because 21312135 - 2⁹ = 21311623 is a prime.

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 8874 + ... + 11016.

It is an arithmetic number, because the mean of its divisors is an integer number (877968).

Almost surely, 2^21312135 is an apocalyptic number.

21312135 is a deficient number, since it is larger than the sum of its proper divisors (20830329).

21312135 is a wasteful number, since it uses less digits than its factorization.

21312135 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2184 (or 2181 counting only the distinct ones).

The product of its digits is 180, while the sum is 18.

The square root of 21312135 is about 4616.5067962692. The cubic root of 21312135 is about 277.2526161498.

Adding to 21312135 its reverse (53121312), we get a palindrome (74433447).

The spelling of 21312135 in words is "twenty-one million, three hundred twelve thousand, one hundred thirty-five".