665529640 has 24 divisors (see below), whose sum is σ = 1497808890. Its totient is φ = 266146592.

The previous prime is 665529577. The next prime is 665529713. The reversal of 665529640 is 46925566.

665529640 is digitally balanced in base 2 and base 6, because in such bases it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 598976676 + 66552964 = 24474^2 + 8158^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 161121 + ... + 165199.

Almost surely, 2^665529640 is an apocalyptic number.

It is an amenable number.

665529640 is an abundant number, since it is smaller than the sum of its proper divisors (832279250).

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

665529640 is an frugal number, since it uses more digits than its factorization.

665529640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8169 (or 4086 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 43.

The square root of 665529640 is about 25797.8611516536. The cubic root of 665529640 is about 873.0835399788.

The spelling of 665529640 in words is "six hundred sixty-five million, five hundred twenty-nine thousand, six hundred forty".