665655540 has 96 divisors (see below), whose sum is σ = 2049062400. Its totient is φ = 160118400.

The previous prime is 665655539. The next prime is 665655559. The reversal of 665655540 is 45556566.

It is a junction number, because it is equal to n+sod(n) for n = 665655492 and 665655501.

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, 82611 + ... + 90309.

It is an arithmetic number, because the mean of its divisors is an integer number (21344400).

Almost surely, 2^665655540 is an apocalyptic number.

665655540 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 665655540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1024531200).

665655540 is an abundant number, since it is smaller than the sum of its proper divisors (1383406860).

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

665655540 is a wasteful number, since it uses less digits than its factorization.

665655540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7853 (or 7851 counting only the distinct ones).

The product of its (nonzero) digits is 540000, while the sum is 42.

The square root of 665655540 is about 25800.3011610330. The cubic root of 665655540 is about 873.1385910141.

The spelling of 665655540 in words is "six hundred sixty-five million, six hundred fifty-five thousand, five hundred forty".