1643656634 has 4 divisors (see below), whose sum is σ = 2465484954. Its totient is φ = 821828316.

The previous prime is 1643656601. The next prime is 1643656669. The reversal of 1643656634 is 4366563461.

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., 967396609 + 676260025 = 31103^2 + 26005^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410914157 + ... + 410914160.

Almost surely, 2^1643656634 is an apocalyptic number.

1643656634 is a deficient number, since it is larger than the sum of its proper divisors (821828320).

1643656634 is an equidigital number, since it uses as much as digits as its factorization.

1643656634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 821828319.

The product of its digits is 933120, while the sum is 44.

The square root of 1643656634 is about 40542.0353953770. The cubic root of 1643656634 is about 1180.1495151922.

The spelling of 1643656634 in words is "one billion, six hundred forty-three million, six hundred fifty-six thousand, six hundred thirty-four".