665497440 has 144 divisors (see below), whose sum is σ = 2319565248. Its totient is φ = 173672448.

The previous prime is 665497381. The next prime is 665497451. The reversal of 665497440 is 44794566.

665497440 is a `hidden beast` number, since 66 + 549 + 7 + 4 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 62764 + ... + 72596.

It is an arithmetic number, because the mean of its divisors is an integer number (16108092).

Almost surely, 2^665497440 is an apocalyptic number.

665497440 is a gapful number since it is divisible by the number (60) 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 665497440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1159782624).

665497440 is an abundant number, since it is smaller than the sum of its proper divisors (1654067808).

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

665497440 is a wasteful number, since it uses less digits than its factorization.

665497440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9901 (or 9890 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 45.

The square root of 665497440 is about 25797.2370613599. The cubic root of 665497440 is about 873.0694590916.

The spelling of 665497440 in words is "six hundred sixty-five million, four hundred ninety-seven thousand, four hundred forty".