821991379 has 8 divisors (see below), whose sum is σ = 896955840. Its totient is φ = 747066600.

The previous prime is 821991367. The next prime is 821991403. The reversal of 821991379 is 973199128.

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 821991379 - 2¹⁹ = 821467091 is a prime.

It is not an unprimeable number, because it can be changed into a prime (821991479) 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 7 ways as a sum of consecutive naturals, for example, 48264 + ... + 63034.

It is an arithmetic number, because the mean of its divisors is an integer number (112119480).

Almost surely, 2^821991379 is an apocalyptic number.

821991379 is a deficient number, since it is larger than the sum of its proper divisors (74964461).

821991379 is a wasteful number, since it uses less digits than its factorization.

821991379 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19841.

The product of its digits is 244944, while the sum is 49.

The square root of 821991379 is about 28670.3920273163. The cubic root of 821991379 is about 936.7472372503.

The spelling of 821991379 in words is "eight hundred twenty-one million, nine hundred ninety-one thousand, three hundred seventy-nine".