821871813 has 8 divisors (see below), whose sum is σ = 1252376128. Its totient is φ = 469641024.

The previous prime is 821871793. The next prime is 821871859. The reversal of 821871813 is 318178128.

821871813 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 821871813 - 2¹³ = 821863621 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821871863) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19568356 + ... + 19568397.

It is an arithmetic number, because the mean of its divisors is an integer number (156547016).

Almost surely, 2^821871813 is an apocalyptic number.

It is an amenable number.

821871813 is a deficient number, since it is larger than the sum of its proper divisors (430504315).

821871813 is a wasteful number, since it uses less digits than its factorization.

821871813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39136763.

The product of its digits is 21504, while the sum is 39.

The square root of 821871813 is about 28668.3067689740. The cubic root of 821871813 is about 936.7018156258.

The spelling of 821871813 in words is "eight hundred twenty-one million, eight hundred seventy-one thousand, eight hundred thirteen".