66442500 has 90 divisors (see below), whose sum is σ = 209943734. Its totient is φ = 17712000.

The previous prime is 66442489. The next prime is 66442507. The reversal of 66442500 is 524466.

It is a happy number.

It can be written as a sum of positive squares in 5 ways, for example, as 15634116 + 50808384 = 3954^2 + 7128^2 .

It is a tau number, because it is divible by the number of its divisors (90).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66442507) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 21024 + ... + 23976.

Almost surely, 2^66442500 is an apocalyptic number.

66442500 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 66442500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104971867).

66442500 is an abundant number, since it is smaller than the sum of its proper divisors (143501234).

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

66442500 is a wasteful number, since it uses less digits than its factorization.

66442500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2983 (or 2963 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 27.

The square root of 66442500 is about 8151.2269015161. The cubic root of 66442500 is about 405.0251470439.

Adding to 66442500 its reverse (524466), we get a palindrome (66966966).

The spelling of 66442500 in words is "sixty-six million, four hundred forty-two thousand, five hundred".