821385431 has 4 divisors (see below), whose sum is σ = 841419264. Its totient is φ = 801351600.

The previous prime is 821385391. The next prime is 821385443. The reversal of 821385431 is 134583128.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 821385431 - 2¹⁴ = 821369047 is a prime.

It is a super-2 number, since 2×821385431² = 1349348052518111522, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 821385391 and 821385400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821385451) 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, 10016855 + ... + 10016936.

It is an arithmetic number, because the mean of its divisors is an integer number (210354816).

Almost surely, 2^821385431 is an apocalyptic number.

821385431 is a deficient number, since it is larger than the sum of its proper divisors (20033833).

821385431 is a wasteful number, since it uses less digits than its factorization.

821385431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20033832.

The product of its digits is 23040, while the sum is 35.

The square root of 821385431 is about 28659.8225919143. The cubic root of 821385431 is about 936.5169997789.

The spelling of 821385431 in words is "eight hundred twenty-one million, three hundred eighty-five thousand, four hundred thirty-one".