66557660 has 48 divisors (see below), whose sum is σ = 151224192. Its totient is φ = 24460800.

The previous prime is 66557657. The next prime is 66557663. The reversal of 66557660 is 6675566.

It is an interprime number because it is at equal distance from previous prime (66557657) and next prime (66557663).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66557663) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 72605 + ... + 73515.

It is an arithmetic number, because the mean of its divisors is an integer number (3150504).

Almost surely, 2^66557660 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 66557660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (75612096).

66557660 is an abundant number, since it is smaller than the sum of its proper divisors (84666532).

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

66557660 is a wasteful number, since it uses less digits than its factorization.

66557660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1214 (or 1212 counting only the distinct ones).

The product of its (nonzero) digits is 226800, while the sum is 41.

The square root of 66557660 is about 8158.2878105642. The cubic root of 66557660 is about 405.2590122877.

The spelling of 66557660 in words is "sixty-six million, five hundred fifty-seven thousand, six hundred sixty".