387866138521 has 9 divisors (see below), whose sum is σ = 389108827933. Its totient is φ = 386627411200.

The previous prime is 387866138509. The next prime is 387866138579. The reversal of 387866138521 is 125831668783.

It is a happy number.

The square root of 387866138521 is 622789.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 75631050121 + 312235088400 = 275011^2 + 558780^2 .

It is not a de Polignac number, because 387866138521 - 2⁷ = 387866138393 is a prime.

It is a super-2 number, since 2×387866138521² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (387866138501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 242264121 + ... + 242265721.

Almost surely, 2^387866138521 is an apocalyptic number.

387866138521 is the 622789-th square number.

387866138521 is the 311395-th centered octagonal number.

It is an amenable number.

387866138521 is a deficient number, since it is larger than the sum of its proper divisors (1242689412).

387866138521 is an frugal number, since it uses more digits than its factorization.

387866138521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3980 (or 1990 counting only the distinct ones).

The product of its digits is 11612160, while the sum is 58.

The spelling of 387866138521 in words is "three hundred eighty-seven billion, eight hundred sixty-six million, one hundred thirty-eight thousand, five hundred twenty-one".