821968249 has 4 divisors (see below), whose sum is σ = 825557860. Its totient is φ = 818378640.

The previous prime is 821968211. The next prime is 821968267. The reversal of 821968249 is 942869128.

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 366914025 + 455054224 = 19155^2 + 21332^2 .

It is a cyclic number.

It is not a de Polignac number, because 821968249 - 2⁹ = 821967737 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (821963249) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1794462 + ... + 1794919.

It is an arithmetic number, because the mean of its divisors is an integer number (206389465).

Almost surely, 2^821968249 is an apocalyptic number.

It is an amenable number.

821968249 is a deficient number, since it is larger than the sum of its proper divisors (3589611).

821968249 is a wasteful number, since it uses less digits than its factorization.

821968249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3589610.

The product of its digits is 497664, while the sum is 49.

The square root of 821968249 is about 28669.9886466667. The cubic root of 821968249 is about 936.7384507969.

The spelling of 821968249 in words is "eight hundred twenty-one million, nine hundred sixty-eight thousand, two hundred forty-nine".