66617856 has 160 divisors (see below), whose sum is σ = 202963200. Its totient is φ = 21565440.

The previous prime is 66617839. The next prime is 66617869. The reversal of 66617856 is 65871666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 843225 + ... + 843303.

It is an arithmetic number, because the mean of its divisors is an integer number (1268520).

Almost surely, 2^66617856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66617856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101481600).

66617856 is an abundant number, since it is smaller than the sum of its proper divisors (136345344).

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

66617856 is an equidigital number, since it uses as much as digits as its factorization.

66617856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 167 (or 145 counting only the distinct ones).

The product of its digits is 362880, while the sum is 45.

The square root of 66617856 is about 8161.9762312812. The cubic root of 66617856 is about 405.3811500991.

The spelling of 66617856 in words is "sixty-six million, six hundred seventeen thousand, eight hundred fifty-six".