1665565440 has 576 divisors, whose sum is σ = 6838013952. Its totient is φ = 335462400.

The previous prime is 1665565423. The next prime is 1665565477. The reversal of 1665565440 is 445655661.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 1665565392 and 1665565401.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 12714175 + ... + 12714305.

It is an arithmetic number, because the mean of its divisors is an integer number (11871552).

Almost surely, 2^1665565440 is an apocalyptic number.

1665565440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1665565440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3419006976).

1665565440 is an abundant number, since it is smaller than the sum of its proper divisors (5172448512).

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

1665565440 is a wasteful number, since it uses less digits than its factorization.

1665565440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 216 (or 202 counting only the distinct ones).

The product of its (nonzero) digits is 432000, while the sum is 42.

The square root of 1665565440 is about 40811.3396006551. The cubic root of 1665565440 is about 1185.3699142458.

The spelling of 1665565440 in words is "one billion, six hundred sixty-five million, five hundred sixty-five thousand, four hundred forty".