393686820 has 36 divisors (see below), whose sum is σ = 1194183900. Its totient is φ = 104983104.

The previous prime is 393686779. The next prime is 393686831. The reversal of 393686820 is 28686393.

It can be written as a sum of positive squares in 2 ways, for example, as 171557604 + 222129216 = 13098^2 + 14904^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (45).

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 in 11 ways as a sum of consecutive naturals, for example, 1093395 + ... + 1093754.

It is an arithmetic number, because the mean of its divisors is an integer number (33171775).

Almost surely, 2^393686820 is an apocalyptic number.

393686820 is a gapful number since it is divisible by the number (30) formed by its first and last digit.

It is an amenable number.

393686820 is an abundant number, since it is smaller than the sum of its proper divisors (800497080).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

393686820 is a wasteful number, since it uses less digits than its factorization.

393686820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2187164 (or 2187159 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 45.

The square root of 393686820 is about 19841.5427827576. The cubic root of 393686820 is about 732.9094000625.

The spelling of 393686820 in words is "three hundred ninety-three million, six hundred eighty-six thousand, eight hundred twenty".