1866321 has 10 divisors (see below), whose sum is σ = 2788082. Its totient is φ = 1244160.

The previous prime is 1866307. The next prime is 1866331. The reversal of 1866321 is 1236681.

It can be written as a sum of positive squares in only one way, i.e., 1347921 + 518400 = 1161^2 + 720^2 .

It is not a de Polignac number, because 1866321 - 2¹⁸ = 1604177 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1866301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 11440 + ... + 11601.

2^1866321 is an apocalyptic number.

It is an amenable number.

1866321 is a deficient number, since it is larger than the sum of its proper divisors (921761).

1866321 is an equidigital number, since it uses as much as digits as its factorization.

1866321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23053 (or 23044 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 1866321 is about 1366.1335952241. The cubic root of 1866321 is about 123.1200493599.

It can be divided in two parts, 1866 and 321, that added together give a 7-th power (2187 = 3⁷).

The spelling of 1866321 in words is "one million, eight hundred sixty-six thousand, three hundred twenty-one".