66611580 has 144 divisors (see below), whose sum is σ = 219864960. Its totient is φ = 15023232.

The previous prime is 66611569. The next prime is 66611617. The reversal of 66611580 is 8511666.

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, 408579 + ... + 408741.

It is an arithmetic number, because the mean of its divisors is an integer number (1526840).

Almost surely, 2^66611580 is an apocalyptic number.

66611580 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 66611580, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109932480).

66611580 is an abundant number, since it is smaller than the sum of its proper divisors (153253380).

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

66611580 is a wasteful number, since it uses less digits than its factorization.

66611580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328 (or 319 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 66611580 is about 8161.5917565142. The cubic root of 66611580 is about 405.3684195183.

It can be divided in two parts, 666 and 11580, that added together give a triangular number (12246 = T₁₅₆).

The spelling of 66611580 in words is "sixty-six million, six hundred eleven thousand, five hundred eighty".