666638424 has 112 divisors (see below), whose sum is σ = 1888966320. Its totient is φ = 220449600.

The previous prime is 666638381. The next prime is 666638429. The reversal of 666638424 is 424836666.

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 666638424.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666638429) by changing a digit.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 880254 + ... + 881010.

Almost surely, 2^666638424 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 666638424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (944483160).

666638424 is an abundant number, since it is smaller than the sum of its proper divisors (1222327896).

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

666638424 is a wasteful number, since it uses less digits than its factorization.

666638424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 932 (or 913 counting only the distinct ones).

The product of its digits is 995328, while the sum is 45.

The square root of 666638424 is about 25819.3420520353. The cubic root of 666638424 is about 873.5681284412.

The spelling of 666638424 in words is "six hundred sixty-six million, six hundred thirty-eight thousand, four hundred twenty-four".