387747821 has 4 divisors (see below), whose sum is σ = 387787932. Its totient is φ = 387707712.

The previous prime is 387747797. The next prime is 387747847. The reversal of 387747821 is 128747783.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 125664100 + 262083721 = 11210^2 + 16189^2 .

It is a cyclic number.

It is not a de Polignac number, because 387747821 - 2²⁶ = 320638957 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 (387741821) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4325 + ... + 28181.

It is an arithmetic number, because the mean of its divisors is an integer number (96946983).

Almost surely, 2^387747821 is an apocalyptic number.

It is an amenable number.

387747821 is a deficient number, since it is larger than the sum of its proper divisors (40111).

387747821 is a wasteful number, since it uses less digits than its factorization.

387747821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40110.

The product of its digits is 526848, while the sum is 47.

The square root of 387747821 is about 19691.3133386273. The cubic root of 387747821 is about 729.2052531736.

The spelling of 387747821 in words is "three hundred eighty-seven million, seven hundred forty-seven thousand, eight hundred twenty-one".