21005235 has 24 divisors (see below), whose sum is σ = 36516480. Its totient is φ = 11169792.

The previous prime is 21005227. The next prime is 21005269. The reversal of 21005235 is 53250012.

It is a happy number.

It is not a de Polignac number, because 21005235 - 2³ = 21005227 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 26931 + ... + 27699.

It is an arithmetic number, because the mean of its divisors is an integer number (1521520).

Almost surely, 2^21005235 is an apocalyptic number.

21005235 is a deficient number, since it is larger than the sum of its proper divisors (15511245).

21005235 is a wasteful number, since it uses less digits than its factorization.

21005235 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1387 (or 1384 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 18.

The square root of 21005235 is about 4583.1468446909. The cubic root of 21005235 is about 275.9153410795.

Adding to 21005235 its reverse (53250012), we get a palindrome (74255247).

The spelling of 21005235 in words is "twenty-one million, five thousand, two hundred thirty-five".