1645020 has 144 divisors (see below), whose sum is σ = 5809440. Its totient is φ = 373248.

The previous prime is 1645019. The next prime is 1645087. The reversal of 1645020 is 205461.

It is a happy number.

1645020 is a `hidden beast` number, since 1 + 645 + 0 + 20 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 1644984 and 1645002.

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 44442 + ... + 44478.

2^1645020 is an apocalyptic number.

1645020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1645020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2904720).

1645020 is an abundant number, since it is smaller than the sum of its proper divisors (4164420).

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

1645020 is a wasteful number, since it uses less digits than its factorization.

1645020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84 (or 79 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 1645020 is about 1282.5833306261. The cubic root of 1645020 is about 118.0475725065.

Multiplying 1645020 by its sum of digits (18), we get a triangular number (29610360 = T₇₆₉₅).

It can be divided in two parts, 164 and 5020, that added together give a square (5184 = 72²).

The spelling of 1645020 in words is "one million, six hundred forty-five thousand, twenty".