1288020321 has 27 divisors (see below), whose sum is σ = 2165491731. Its totient is φ = 735580944.

The previous prime is 1288020277. The next prime is 1288020329. The reversal of 1288020321 is 1230208821.

The square root of 1288020321 is 35889.

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

It can be written as a sum of positive squares in only one way, i.e., 242144721 + 1045875600 = 15561^2 + 32340^2 .

It is not a de Polignac number, because 1288020321 - 2¹⁷ = 1287889249 is a prime.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (1288020329) 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 26 ways as a sum of consecutive naturals, for example, 752815 + ... + 754523.

Almost surely, 2^1288020321 is an apocalyptic number.

1288020321 is the 35889-th square number.

1288020321 is the 17945-th centered octagonal number.

It is an amenable number.

1288020321 is a deficient number, since it is larger than the sum of its proper divisors (877471410).

1288020321 is an frugal number, since it uses more digits than its factorization.

1288020321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3438 (or 1719 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The cubic root of 1288020321 is about 1088.0300870361.

The spelling of 1288020321 in words is "one billion, two hundred eighty-eight million, twenty thousand, three hundred twenty-one".