1866409 has 2 divisors, whose sum is σ = 1866410. Its totient is φ = 1866408.

The previous prime is 1866373. The next prime is 1866437. The reversal of 1866409 is 9046681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1440000 + 426409 = 1200^2 + 653^2 .

It is a cyclic number.

It is not a de Polignac number, because 1866409 - 2⁷ = 1866281 is a prime.

1866409 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (1866439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 933204 + 933205.

It is an arithmetic number, because the mean of its divisors is an integer number (933205).

2^1866409 is an apocalyptic number.

It is an amenable number.

1866409 is a deficient number, since it is larger than the sum of its proper divisors (1).

1866409 is an equidigital number, since it uses as much as digits as its factorization.

1866409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 1866409 is about 1366.1658025291. The cubic root of 1866409 is about 123.1219844315.

The spelling of 1866409 in words is "one million, eight hundred sixty-six thousand, four hundred nine".