1645820 has 24 divisors (see below), whose sum is σ = 3770928. Its totient is φ = 598400.

The previous prime is 1645801. The next prime is 1645829. The reversal of 1645820 is 285461.

It is a self number, because there is not a number n which added to its sum of digits gives 1645820.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1645829) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3521 + ... + 3960.

It is an arithmetic number, because the mean of its divisors is an integer number (157122).

2^1645820 is an apocalyptic number.

1645820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1645820 is an abundant number, since it is smaller than the sum of its proper divisors (2125108).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1645820 is a wasteful number, since it uses less digits than its factorization.

1645820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7501 (or 7499 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 1645820 is about 1282.8951632928. The cubic root of 1645820 is about 118.0667055572.

The spelling of 1645820 in words is "one million, six hundred forty-five thousand, eight hundred twenty".