1645989 has 16 divisors (see below), whose sum is σ = 2350080. Its totient is φ = 1021680.

The previous prime is 1645979. The next prime is 1645999. The reversal of 1645989 is 9895461.

It is an interprime number because it is at equal distance from previous prime (1645979) and next prime (1645999).

It is not a de Polignac number, because 1645989 - 2⁸ = 1645733 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1645989.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645909) 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 15 ways as a sum of consecutive naturals, for example, 3604 + ... + 4034.

It is an arithmetic number, because the mean of its divisors is an integer number (146880).

2^1645989 is an apocalyptic number.

1645989 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

It is an amenable number.

1645989 is a deficient number, since it is larger than the sum of its proper divisors (704091).

1645989 is a wasteful number, since it uses less digits than its factorization.

1645989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 520.

The product of its digits is 77760, while the sum is 42.

The square root of 1645989 is about 1282.9610282468. The cubic root of 1645989 is about 118.0707466208.

The spelling of 1645989 in words is "one million, six hundred forty-five thousand, nine hundred eighty-nine".