1643043946 has 4 divisors (see below), whose sum is σ = 2464565922. Its totient is φ = 821521972.

The previous prime is 1643043929. The next prime is 1643044027. The reversal of 1643043946 is 6493403461.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 1580460025 + 62583921 = 39755^2 + 7911^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 1643043899 and 1643043908.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410760985 + ... + 410760988.

Almost surely, 2^1643043946 is an apocalyptic number.

1643043946 is a deficient number, since it is larger than the sum of its proper divisors (821521976).

1643043946 is an equidigital number, since it uses as much as digits as its factorization.

1643043946 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 821521975.

The product of its (nonzero) digits is 186624, while the sum is 40.

The square root of 1643043946 is about 40534.4784843718. The cubic root of 1643043946 is about 1180.0028598035.

The spelling of 1643043946 in words is "one billion, six hundred forty-three million, forty-three thousand, nine hundred forty-six".