21283805 has 4 divisors (see below), whose sum is σ = 25540572. Its totient is φ = 17027040.

The previous prime is 21283777. The next prime is 21283841. The reversal of 21283805 is 50838212.

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 3076516 + 18207289 = 1754^2 + 4267^2 .

It is not a de Polignac number, because 21283805 - 2²⁴ = 4506589 is a prime.

It is a Duffinian number.

It is a congruent 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, 2128376 + ... + 2128385.

It is an arithmetic number, because the mean of its divisors is an integer number (6385143).

Almost surely, 2^21283805 is an apocalyptic number.

It is an amenable number.

21283805 is a deficient number, since it is larger than the sum of its proper divisors (4256767).

21283805 is an equidigital number, since it uses as much as digits as its factorization.

21283805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4256766.

The product of its (nonzero) digits is 3840, while the sum is 29.

The square root of 21283805 is about 4613.4374386134. The cubic root of 21283805 is about 277.1297119997.

The spelling of 21283805 in words is "twenty-one million, two hundred eighty-three thousand, eight hundred five".