643663790 has 32 divisors (see below), whose sum is σ = 1444483584. Its totient is φ = 200622240.

The previous prime is 643663751. The next prime is 643663829. The reversal of 643663790 is 97366346.

It is an interprime number because it is at equal distance from previous prime (643663751) and next prime (643663829).

It is a Curzon number.

It is a congruent number.

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 in 15 ways as a sum of consecutive naturals, for example, 417194 + ... + 418733.

It is an arithmetic number, because the mean of its divisors is an integer number (45140112).

Almost surely, 2^643663790 is an apocalyptic number.

643663790 is an abundant number, since it is smaller than the sum of its proper divisors (800819794).

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

643663790 is a wasteful number, since it uses less digits than its factorization.

643663790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 835952.

The product of its (nonzero) digits is 489888, while the sum is 44.

The square root of 643663790 is about 25370.5299511067. The cubic root of 643663790 is about 863.4152055184.

The spelling of 643663790 in words is "six hundred forty-three million, six hundred sixty-three thousand, seven hundred ninety".