66665550 has 96 divisors (see below), whose sum is σ = 190559232. Its totient is φ = 15108480.

The previous prime is 66665537. The next prime is 66665567. The reversal of 66665550 is 5556666.

It is a happy number.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 66665499 and 66665508.

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, 181467 + ... + 181833.

It is an arithmetic number, because the mean of its divisors is an integer number (1984992).

Almost surely, 2^66665550 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66665550, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (95279616).

66665550 is an abundant number, since it is smaller than the sum of its proper divisors (123893682).

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

66665550 is a wasteful number, since it uses less digits than its factorization.

66665550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 562 (or 557 counting only the distinct ones).

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

The square root of 66665550 is about 8164.8974274023. The cubic root of 66665550 is about 405.4778690948.

The spelling of 66665550 in words is "sixty-six million, six hundred sixty-five thousand, five hundred fifty".