1643980 has 24 divisors (see below), whose sum is σ = 3718512. Its totient is φ = 606912.

The previous prime is 1643969. The next prime is 1643987. The reversal of 1643980 is 893461.

It is not an unprimeable number, because it can be changed into a prime (1643987) 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, 2902 + ... + 3421.

It is an arithmetic number, because the mean of its divisors is an integer number (154938).

2^1643980 is an apocalyptic number.

1643980 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1643980 is an abundant number, since it is smaller than the sum of its proper divisors (2074532).

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

1643980 is a wasteful number, since it uses less digits than its factorization.

1643980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6345 (or 6343 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 31.

The square root of 1643980 is about 1282.1778347796. The cubic root of 1643980 is about 118.0226902646.

The spelling of 1643980 in words is "one million, six hundred forty-three thousand, nine hundred eighty".