665210640 has 40 divisors (see below), whose sum is σ = 2062153728. Its totient is φ = 177389440.

The previous prime is 665210597. The next prime is 665210641. The reversal of 665210640 is 46012566.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 665210598 and 665210607.

It is not an unprimeable number, because it can be changed into a prime (665210641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1385616 + ... + 1386095.

Almost surely, 2^665210640 is an apocalyptic number.

665210640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

665210640 is an abundant number, since it is smaller than the sum of its proper divisors (1396943088).

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

665210640 is a wasteful number, since it uses less digits than its factorization.

665210640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2771727 (or 2771721 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 665210640 is about 25791.6777275151. The cubic root of 665210640 is about 872.9440229470.

The spelling of 665210640 in words is "six hundred sixty-five million, two hundred ten thousand, six hundred forty".