643319892 has 18 divisors (see below), whose sum is σ = 1626169818. Its totient is φ = 214439952.

The previous prime is 643319881. The next prime is 643319923. The reversal of 643319892 is 298913346.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 593701956 + 49617936 = 24366^2 + 7044^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8934963 + ... + 8935034.

Almost surely, 2^643319892 is an apocalyptic number.

It is an amenable number.

643319892 is an abundant number, since it is smaller than the sum of its proper divisors (982849926).

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

643319892 is a wasteful number, since it uses less digits than its factorization.

643319892 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17870007 (or 17870002 counting only the distinct ones).

The product of its digits is 279936, while the sum is 45.

The square root of 643319892 is about 25363.7515363954. The cubic root of 643319892 is about 863.2614090470.

The spelling of 643319892 in words is "six hundred forty-three million, three hundred nineteen thousand, eight hundred ninety-two".