643665740 has 12 divisors (see below), whose sum is σ = 1351698096. Its totient is φ = 257466288.

The previous prime is 643665739. The next prime is 643665767. The reversal of 643665740 is 47566346.

It is a super-3 number, since 3×643665740³ (a number of 27 digits) contains 333 as substring.

It is a hoax number, since the sum of its digits (41) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16091624 + ... + 16091663.

It is an arithmetic number, because the mean of its divisors is an integer number (112641508).

Almost surely, 2^643665740 is an apocalyptic number.

It is an amenable number.

643665740 is an abundant number, since it is smaller than the sum of its proper divisors (708032356).

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

643665740 is a wasteful number, since it uses less digits than its factorization.

643665740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32183296 (or 32183294 counting only the distinct ones).

The product of its (nonzero) digits is 362880, while the sum is 41.

The square root of 643665740 is about 25370.5683814928. The cubic root of 643665740 is about 863.4160774321.

The spelling of 643665740 in words is "six hundred forty-three million, six hundred sixty-five thousand, seven hundred forty".