21393305 has 4 divisors (see below), whose sum is σ = 25671972. Its totient is φ = 17114640.

The previous prime is 21393299. The next prime is 21393313. The reversal of 21393305 is 50339312.

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

It can be written as a sum of positive squares in 2 ways, for example, as 9024016 + 12369289 = 3004^2 + 3517^2 .

It is not a de Polignac number, because 21393305 - 2⁸ = 21393049 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2139326 + ... + 2139335.

It is an arithmetic number, because the mean of its divisors is an integer number (6417993).

Almost surely, 2^21393305 is an apocalyptic number.

It is an amenable number.

21393305 is a deficient number, since it is larger than the sum of its proper divisors (4278667).

21393305 is an equidigital number, since it uses as much as digits as its factorization.

21393305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4278666.

The product of its (nonzero) digits is 2430, while the sum is 26.

The square root of 21393305 is about 4625.2897206553. The cubic root of 21393305 is about 277.6041542854.

The spelling of 21393305 in words is "twenty-one million, three hundred ninety-three thousand, three hundred five".