66661020 has 72 divisors (see below), whose sum is σ = 203330400. Its totient is φ = 17677440.

The previous prime is 66661009. The next prime is 66661043. The reversal of 66661020 is 2016666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 34890 + ... + 36750.

Almost surely, 2^66661020 is an apocalyptic number.

66661020 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 66661020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (101665200).

66661020 is an abundant number, since it is smaller than the sum of its proper divisors (136669380).

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

66661020 is a wasteful number, since it uses less digits than its factorization.

66661020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2075 (or 2070 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 66661020 is about 8164.6200156529. The cubic root of 66661020 is about 405.4686846592.

Adding to 66661020 its reverse (2016666), we get a palindrome (68677686).

The spelling of 66661020 in words is "sixty-six million, six hundred sixty-one thousand, twenty".