21315235 has 4 divisors (see below), whose sum is σ = 25578288. Its totient is φ = 17052184.

The previous prime is 21315223. The next prime is 21315241. The reversal of 21315235 is 53251312.

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

It is a cyclic number.

It is not a de Polignac number, because 21315235 - 2¹³ = 21307043 is a prime.

It is a Duffinian 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 in 3 ways as a sum of consecutive naturals, for example, 2131519 + ... + 2131528.

It is an arithmetic number, because the mean of its divisors is an integer number (6394572).

Almost surely, 2^21315235 is an apocalyptic number.

21315235 is a deficient number, since it is larger than the sum of its proper divisors (4263053).

21315235 is an equidigital number, since it uses as much as digits as its factorization.

21315235 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4263052.

The product of its digits is 900, while the sum is 22.

The square root of 21315235 is about 4616.8425357597. The cubic root of 21315235 is about 277.2660582794.

Adding to 21315235 its reverse (53251312), we get a palindrome (74566547).

The spelling of 21315235 in words is "twenty-one million, three hundred fifteen thousand, two hundred thirty-five".