21052305 has 24 divisors (see below), whose sum is σ = 37844352. Its totient is φ = 11227248.

The previous prime is 21052301. The next prime is 21052331. The reversal of 21052305 is 50325012.

It is a happy number.

It is not a de Polignac number, because 21052305 - 2² = 21052301 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (21052301) 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 23 ways as a sum of consecutive naturals, for example, 7449 + ... + 9878.

It is an arithmetic number, because the mean of its divisors is an integer number (1576848).

Almost surely, 2^21052305 is an apocalyptic number.

It is an amenable number.

21052305 is a deficient number, since it is larger than the sum of its proper divisors (16792047).

21052305 is an equidigital number, since it uses as much as digits as its factorization.

21052305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17347 (or 17335 counting only the distinct ones).

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

The square root of 21052305 is about 4588.2790891575. The cubic root of 21052305 is about 276.1212841248.

Adding to 21052305 its reverse (50325012), we get a palindrome (71377317).

The spelling of 21052305 in words is "twenty-one million, fifty-two thousand, three hundred five".