821864404 has 6 divisors (see below), whose sum is σ = 1438262714. Its totient is φ = 410932200.

The previous prime is 821864377. The next prime is 821864429. The reversal of 821864404 is 404468128.

It can be written as a sum of positive squares in only one way, i.e., 548028100 + 273836304 = 23410^2 + 16548^2 .

It is a super-2 number, since 2×821864404² = 1350922197124550432, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 102733047 + ... + 102733054.

Almost surely, 2^821864404 is an apocalyptic number.

It is an amenable number.

821864404 is a deficient number, since it is larger than the sum of its proper divisors (616398310).

821864404 is a wasteful number, since it uses less digits than its factorization.

821864404 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 205466105 (or 205466103 counting only the distinct ones).

The product of its (nonzero) digits is 49152, while the sum is 37.

The square root of 821864404 is about 28668.1775493316. The cubic root of 821864404 is about 936.6990008946.

The spelling of 821864404 in words is "eight hundred twenty-one million, eight hundred sixty-four thousand, four hundred four".