665331840 has 256 divisors, whose sum is σ = 2381904000. Its totient is φ = 175509504.

The previous prime is 665331809. The next prime is 665331851. The reversal of 665331840 is 48133566.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 665331795 and 665331804.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2401782 + ... + 2402058.

Almost surely, 2^665331840 is an apocalyptic number.

665331840 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 665331840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1190952000).

665331840 is an abundant number, since it is smaller than the sum of its proper divisors (1716572160).

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

665331840 is a wasteful number, since it uses less digits than its factorization.

665331840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 444 (or 426 counting only the distinct ones).

The product of its (nonzero) digits is 51840, while the sum is 36.

The square root of 665331840 is about 25794.0272156172. The cubic root of 665331840 is about 872.9970359248.

The spelling of 665331840 in words is "six hundred sixty-five million, three hundred thirty-one thousand, eight hundred forty".