665618440 has 32 divisors (see below), whose sum is σ = 1549287000. Its totient is φ = 257065984.

The previous prime is 665618399. The next prime is 665618441. The reversal of 665618440 is 44816566.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 415915236 + 249703204 = 20394^2 + 15802^2 .

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 665618393 and 665618402.

It is not an unprimeable number, because it can be changed into a prime (665618441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 285745 + ... + 288064.

Almost surely, 2^665618440 is an apocalyptic number.

It is an amenable number.

665618440 is an abundant number, since it is smaller than the sum of its proper divisors (883668560).

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

665618440 is a wasteful number, since it uses less digits than its factorization.

665618440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 573849 (or 573845 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 40.

The square root of 665618440 is about 25799.5821671592. The cubic root of 665618440 is about 873.1223693892.

The spelling of 665618440 in words is "six hundred sixty-five million, six hundred eighteen thousand, four hundred forty".