21873205 has 4 divisors (see below), whose sum is σ = 26247852. Its totient is φ = 17498560.

The previous prime is 21873191. The next prime is 21873217. The reversal of 21873205 is 50237812.

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 11336689 + 10536516 = 3367^2 + 3246^2 .

It is not a de Polignac number, because 21873205 - 2⁷ = 21873077 is a prime.

It is a Duffinian number.

It is a congruent 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, 2187316 + ... + 2187325.

It is an arithmetic number, because the mean of its divisors is an integer number (6561963).

Almost surely, 2^21873205 is an apocalyptic number.

It is an amenable number.

21873205 is a deficient number, since it is larger than the sum of its proper divisors (4374647).

21873205 is an equidigital number, since it uses as much as digits as its factorization.

21873205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4374646.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 21873205 is about 4676.8798359590. The cubic root of 21873205 is about 279.6645856096.

The spelling of 21873205 in words is "twenty-one million, eight hundred seventy-three thousand, two hundred five".