387781021 has 4 divisors (see below), whose sum is σ = 389020252. Its totient is φ = 386541792.

The previous prime is 387780977. The next prime is 387781027. The reversal of 387781021 is 120187783.

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 77528025 + 310252996 = 8805^2 + 17614^2 .

It is a cyclic number.

It is not a de Polignac number, because 387781021 - 2⁷ = 387780893 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 (387781027) 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, 619146 + ... + 619771.

It is an arithmetic number, because the mean of its divisors is an integer number (97255063).

Almost surely, 2^387781021 is an apocalyptic number.

It is an amenable number.

387781021 is a deficient number, since it is larger than the sum of its proper divisors (1239231).

387781021 is a wasteful number, since it uses less digits than its factorization.

387781021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1239230.

The product of its (nonzero) digits is 18816, while the sum is 37.

The square root of 387781021 is about 19692.1563319003. The cubic root of 387781021 is about 729.2260647442.

The spelling of 387781021 in words is "three hundred eighty-seven million, seven hundred eighty-one thousand, twenty-one".