389366821 has 4 divisors (see below), whose sum is σ = 390696012. Its totient is φ = 388037632.

The previous prime is 389366729. The next prime is 389366833. The reversal of 389366821 is 128663983.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 128663983 = 7 ⋅18380569.

It can be written as a sum of positive squares in 2 ways, for example, as 377874721 + 11492100 = 19439^2 + 3390^2 .

It is a cyclic number.

It is not a de Polignac number, because 389366821 - 2¹⁹ = 388842533 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 (389366321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 664156 + ... + 664741.

It is an arithmetic number, because the mean of its divisors is an integer number (97674003).

Almost surely, 2^389366821 is an apocalyptic number.

It is an amenable number.

389366821 is a deficient number, since it is larger than the sum of its proper divisors (1329191).

389366821 is a wasteful number, since it uses less digits than its factorization.

389366821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1329190.

The product of its digits is 373248, while the sum is 46.

The square root of 389366821 is about 19732.3800135716. The cubic root of 389366821 is about 730.2187503561.

The spelling of 389366821 in words is "three hundred eighty-nine million, three hundred sixty-six thousand, eight hundred twenty-one".