1643969 has 2 divisors, whose sum is σ = 1643970. Its totient is φ = 1643968.

The previous prime is 1643963. The next prime is 1643987. The reversal of 1643969 is 9693461.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1181569 + 462400 = 1087^2 + 680^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1643969 is a prime.

It is a super-2 number, since 2×1643969² = 5405268145922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1643963) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 821984 + 821985.

It is an arithmetic number, because the mean of its divisors is an integer number (821985).

2^1643969 is an apocalyptic number.

It is an amenable number.

1643969 is a deficient number, since it is larger than the sum of its proper divisors (1).

1643969 is an equidigital number, since it uses as much as digits as its factorization.

1643969 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34992, while the sum is 38.

The square root of 1643969 is about 1282.1735451958. The cubic root of 1643969 is about 118.0224270309.

The spelling of 1643969 in words is "one million, six hundred forty-three thousand, nine hundred sixty-nine".