643790386 has 4 divisors (see below), whose sum is σ = 965685582. Its totient is φ = 321895192.

The previous prime is 643790383. The next prime is 643790429. The reversal of 643790386 is 683097346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 683097346 = 2 ⋅341548673.

It can be written as a sum of positive squares in only one way, i.e., 402764761 + 241025625 = 20069^2 + 15525^2 .

It is a super-2 number, since 2×643790386² = 828932122212057992, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (643790383) by changing a digit.

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, 160947595 + ... + 160947598.

Almost surely, 2^643790386 is an apocalyptic number.

643790386 is a deficient number, since it is larger than the sum of its proper divisors (321895196).

643790386 is a wasteful number, since it uses less digits than its factorization.

643790386 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321895195.

The product of its (nonzero) digits is 653184, while the sum is 46.

The square root of 643790386 is about 25373.0247704132. The cubic root of 643790386 is about 863.4718074006.

The spelling of 643790386 in words is "six hundred forty-three million, seven hundred ninety thousand, three hundred eighty-six".