66440000 has 140 divisors (see below), whose sum is σ = 180917088. Its totient is φ = 24000000.

The previous prime is 66439981. The next prime is 66440009. The reversal of 66440000 is 4466.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66440009) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 439925 + ... + 440075.

Almost surely, 2^66440000 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 66440000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (90458544).

66440000 is an abundant number, since it is smaller than the sum of its proper divisors (114477088).

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

66440000 is a wasteful number, since it uses less digits than its factorization.

66440000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194 (or 169 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 66440000 is about 8151.0735489259. The cubic root of 66440000 is about 405.0200670847.

Adding to 66440000 its reverse (4466), we get a palindrome (66444466).

The spelling of 66440000 in words is "sixty-six million, four hundred forty thousand".