643353660 has 36 divisors (see below), whose sum is σ = 1951506648. Its totient is φ = 171560928.

The previous prime is 643353653. The next prime is 643353671. The reversal of 643353660 is 66353346.

It is a happy number.

643353660 is a `hidden beast` number, since 64 + 3 + 3 + 536 + 60 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1786914 + ... + 1787273.

It is an arithmetic number, because the mean of its divisors is an integer number (54208518).

Almost surely, 2^643353660 is an apocalyptic number.

643353660 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

643353660 is an abundant number, since it is smaller than the sum of its proper divisors (1308152988).

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

643353660 is a wasteful number, since it uses less digits than its factorization.

643353660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3574202 (or 3574197 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 36.

The square root of 643353660 is about 25364.4172020569. The cubic root of 643353660 is about 863.2765130420.

The spelling of 643353660 in words is "six hundred forty-three million, three hundred fifty-three thousand, six hundred sixty".