665606550 has 96 divisors (see below), whose sum is σ = 1951660800. Its totient is φ = 146885760.

The previous prime is 665606533. The next prime is 665606561. The reversal of 665606550 is 55606566.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 665606499 and 665606508.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 19521 + ... + 41379.

It is an arithmetic number, because the mean of its divisors is an integer number (20329800).

Almost surely, 2^665606550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 665606550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (975830400).

665606550 is an abundant number, since it is smaller than the sum of its proper divisors (1286054250).

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

665606550 is a wasteful number, since it uses less digits than its factorization.

665606550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21910 (or 21905 counting only the distinct ones).

The product of its (nonzero) digits is 162000, while the sum is 39.

The square root of 665606550 is about 25799.3517360417. The cubic root of 665606550 is about 873.1171704713.

The spelling of 665606550 in words is "six hundred sixty-five million, six hundred six thousand, five hundred fifty".