821920879 has 16 divisors (see below), whose sum is σ = 939496320. Its totient is φ = 712327680.

The previous prime is 821920861. The next prime is 821920889. The reversal of 821920879 is 978029128.

It is a cyclic number.

It is not a de Polignac number, because 821920879 - 2¹³ = 821912687 is a prime.

It is a super-2 number, since 2×821920879² = 1351107862672265282, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821920889) 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 15 ways as a sum of consecutive naturals, for example, 90937 + ... + 99565.

It is an arithmetic number, because the mean of its divisors is an integer number (58718520).

Almost surely, 2^821920879 is an apocalyptic number.

821920879 is a deficient number, since it is larger than the sum of its proper divisors (117575441).

821920879 is a wasteful number, since it uses less digits than its factorization.

821920879 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9090.

The product of its (nonzero) digits is 145152, while the sum is 46.

The square root of 821920879 is about 28669.1625095677. The cubic root of 821920879 is about 936.7204557170.

The spelling of 821920879 in words is "eight hundred twenty-one million, nine hundred twenty thousand, eight hundred seventy-nine".