665509940 has 24 divisors (see below), whose sum is σ = 1399571880. Its totient is φ = 265822848.

The previous prime is 665509937. The next prime is 665509961. The reversal of 665509940 is 49905566.

It can be written as a sum of positive squares in 4 ways, for example, as 21771556 + 643738384 = 4666^2 + 25372^2 .

It is a junction number, because it is equal to n+sod(n) for n = 665509891 and 665509900.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9287 + ... + 37646.

It is an arithmetic number, because the mean of its divisors is an integer number (58315495).

Almost surely, 2^665509940 is an apocalyptic number.

It is an amenable number.

665509940 is an abundant number, since it is smaller than the sum of its proper divisors (734061940).

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

665509940 is a wasteful number, since it uses less digits than its factorization.

665509940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47651 (or 47649 counting only the distinct ones).

The product of its (nonzero) digits is 291600, while the sum is 44.

The square root of 665509940 is about 25797.4793342295. The cubic root of 665509940 is about 873.0749253285.

The spelling of 665509940 in words is "six hundred sixty-five million, five hundred nine thousand, nine hundred forty".