1128220921 has 3 divisors (see below), whose sum is σ = 1128254511. Its totient is φ = 1128187332.

The previous prime is 1128220897. The next prime is 1128220927. The reversal of 1128220921 is 1290228211.

The square root of 1128220921 is 33589.

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

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 only one way, i.e., 1114825321 + 13395600 = 33389^2 + 3660^2 .

It is not a de Polignac number, because 1128220921 - 2¹¹ = 1128218873 is a prime.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1128220921.

It is not an unprimeable number, because it can be changed into a prime (1128220927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 16795 + ... + 50383.

It is an arithmetic number, because the mean of its divisors is an integer number (376084837).

Almost surely, 2^1128220921 is an apocalyptic number.

1128220921 is the 33589-th square number.

1128220921 is the 16795-th centered octagonal number.

It is an amenable number.

1128220921 is a deficient number, since it is larger than the sum of its proper divisors (33590).

1128220921 is an frugal number, since it uses more digits than its factorization.

1128220921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67178 (or 33589 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 28.

The cubic root of 1128220921 is about 1041.0335266219.

The spelling of 1128220921 in words is "one billion, one hundred twenty-eight million, two hundred twenty thousand, nine hundred twenty-one".