21831245 has 8 divisors (see below), whose sum is σ = 26222616. Its totient is φ = 17448256.

The previous prime is 21831217. The next prime is 21831253. The reversal of 21831245 is 54213812.

It can be written as a sum of positive squares in 4 ways, for example, as 5396329 + 16434916 = 2323^2 + 4054^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21831245 - 2⁶ = 21831181 is a prime.

It is a Duffinian number.

It is a Curzon 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 7 ways as a sum of consecutive naturals, for example, 8759 + ... + 10971.

It is an arithmetic number, because the mean of its divisors is an integer number (3277827).

Almost surely, 2^21831245 is an apocalyptic number.

It is an amenable number.

21831245 is a deficient number, since it is larger than the sum of its proper divisors (4391371).

21831245 is a wasteful number, since it uses less digits than its factorization.

21831245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4191.

The product of its digits is 1920, while the sum is 26.

The square root of 21831245 is about 4672.3917857988. The cubic root of 21831245 is about 279.4856415894.

The spelling of 21831245 in words is "twenty-one million, eight hundred thirty-one thousand, two hundred forty-five".