821678834 has 8 divisors (see below), whose sum is σ = 1244721708. Its totient is φ = 406771600.

The previous prime is 821678831. The next prime is 821678857. The reversal of 821678834 is 438876128.

It can be written as a sum of positive squares in 2 ways, for example, as 573458809 + 248220025 = 23947^2 + 15755^2 .

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

It is a super-2 number, since 2×821678834² = 1350312212487199112, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (821678831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2033657 + ... + 2034060.

Almost surely, 2^821678834 is an apocalyptic number.

821678834 is a deficient number, since it is larger than the sum of its proper divisors (423042874).

821678834 is a wasteful number, since it uses less digits than its factorization.

821678834 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4067820.

The product of its digits is 516096, while the sum is 47.

The square root of 821678834 is about 28664.9408511513. The cubic root of 821678834 is about 936.6284960291.

The spelling of 821678834 in words is "eight hundred twenty-one million, six hundred seventy-eight thousand, eight hundred thirty-four".