388918681 has 4 divisors (see below), whose sum is σ = 402329700. Its totient is φ = 375507664.

The previous prime is 388918667. The next prime is 388918709. The reversal of 388918681 is 186819883.

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

It can be written as a sum of positive squares in 2 ways, for example, as 212693056 + 176225625 = 14584^2 + 13275^2 .

It is a cyclic number.

It is not a de Polignac number, because 388918681 - 2⁷ = 388918553 is a prime.

It is a super-2 number, since 2×388918681² = 302515480861559522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (388918631) 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, 6705466 + ... + 6705523.

It is an arithmetic number, because the mean of its divisors is an integer number (100582425).

Almost surely, 2^388918681 is an apocalyptic number.

It is an amenable number.

388918681 is a deficient number, since it is larger than the sum of its proper divisors (13411019).

388918681 is a wasteful number, since it uses less digits than its factorization.

388918681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13411018.

The product of its digits is 663552, while the sum is 52.

The square root of 388918681 is about 19721.0212970830. The cubic root of 388918681 is about 729.9384954750.

The spelling of 388918681 in words is "three hundred eighty-eight million, nine hundred eighteen thousand, six hundred eighty-one".