821439394 has 4 divisors (see below), whose sum is σ = 1232159094. Its totient is φ = 410719696.

The previous prime is 821439349. The next prime is 821439431. The reversal of 821439394 is 493934128.

821439394 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in only one way, i.e., 818246025 + 3193369 = 28605^2 + 1787^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 821439394.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 205359847 + ... + 205359850.

Almost surely, 2^821439394 is an apocalyptic number.

821439394 is a deficient number, since it is larger than the sum of its proper divisors (410719700).

821439394 is a wasteful number, since it uses less digits than its factorization.

821439394 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 410719699.

The product of its digits is 186624, while the sum is 43.

The square root of 821439394 is about 28660.7640163342. The cubic root of 821439394 is about 936.5375082833.

The spelling of 821439394 in words is "eight hundred twenty-one million, four hundred thirty-nine thousand, three hundred ninety-four".