387656721 has 9 divisors (see below), whose sum is σ = 560033929. Its totient is φ = 258398436.

The previous prime is 387656701. The next prime is 387656723. The reversal of 387656721 is 127656783.

The square root of 387656721 is 19689.

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

387656721 is a `hidden beast` number, since 3 + 87 + 6 + 567 + 2 + 1 = 666.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 387656721 - 2²¹ = 385559569 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (387656723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 55786 + ... + 62348.

Almost surely, 2^387656721 is an apocalyptic number.

387656721 is the 19689-th square number.

387656721 is the 9845-th centered octagonal number.

It is an amenable number.

387656721 is a deficient number, since it is larger than the sum of its proper divisors (172377208).

387656721 is an frugal number, since it uses more digits than its factorization.

387656721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13132 (or 6566 counting only the distinct ones).

The product of its digits is 423360, while the sum is 45.

The cubic root of 387656721 is about 729.1481406225.

The spelling of 387656721 in words is "three hundred eighty-seven million, six hundred fifty-six thousand, seven hundred twenty-one".