21312235 has 16 divisors (see below), whose sum is σ = 29304576. Its totient is φ = 14575968.

The previous prime is 21312233. The next prime is 21312257. The reversal of 21312235 is 53221312.

It is a cyclic number.

It is not a de Polignac number, because 21312235 - 2¹ = 21312233 is a prime.

It is a super-2 number, since 2×21312235² = 908422721390450, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21312233) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 22032 + ... + 22978.

It is an arithmetic number, because the mean of its divisors is an integer number (1831536).

Almost surely, 2^21312235 is an apocalyptic number.

21312235 is a deficient number, since it is larger than the sum of its proper divisors (7992341).

21312235 is an equidigital number, since it uses as much as digits as its factorization.

21312235 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1602.

The product of its digits is 360, while the sum is 19.

The square root of 21312235 is about 4616.5176269565. The cubic root of 21312235 is about 277.2530497873.

Adding to 21312235 its reverse (53221312), we get a palindrome (74533547).

The spelling of 21312235 in words is "twenty-one million, three hundred twelve thousand, two hundred thirty-five".