386640821 has 12 divisors (see below), whose sum is σ = 460228032. Its totient is φ = 323697528.

The previous prime is 386640811. The next prime is 386640857. The reversal of 386640821 is 128046683.

It is a happy number.

It is not a de Polignac number, because 386640821 - 2⁶ = 386640757 is a prime.

It is a super-2 number, since 2×386640821² = 298982248927108082, 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 (386640811) 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 11 ways as a sum of consecutive naturals, for example, 89645 + ... + 93858.

It is an arithmetic number, because the mean of its divisors is an integer number (38352336).

Almost surely, 2^386640821 is an apocalyptic number.

It is an amenable number.

386640821 is a deficient number, since it is larger than the sum of its proper divisors (73587211).

386640821 is a wasteful number, since it uses less digits than its factorization.

386640821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 183560 (or 183553 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 38.

The square root of 386640821 is about 19663.1844063977. The cubic root of 386640821 is about 728.5106439522.

The spelling of 386640821 in words is "three hundred eighty-six million, six hundred forty thousand, eight hundred twenty-one".