1643920 has 20 divisors (see below), whose sum is σ = 3822300. Its totient is φ = 657536.

The previous prime is 1643893. The next prime is 1643959. The reversal of 1643920 is 293461.

It can be written as a sum of positive squares in 2 ways, for example, as 1218816 + 425104 = 1104^2 + 652^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is an Ulam number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10195 + ... + 10354.

It is an arithmetic number, because the mean of its divisors is an integer number (191115).

2^1643920 is an apocalyptic number.

1643920 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1643920 is an abundant number, since it is smaller than the sum of its proper divisors (2178380).

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

1643920 is a wasteful number, since it uses less digits than its factorization.

1643920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20562 (or 20556 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 1643920 is about 1282.1544368757. The cubic root of 1643920 is about 118.0212544305.

The spelling of 1643920 in words is "one million, six hundred forty-three thousand, nine hundred twenty".