66664400 has 120 divisors (see below), whose sum is σ = 177592800. Its totient is φ = 23846400.

The previous prime is 66664391. The next prime is 66664421. The reversal of 66664400 is 446666.

It is a happy number.

It is a hoax number, since the sum of its digits (32) coincides with the sum of the digits of its distinct prime factors.

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

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, 479531 + ... + 479669.

It is an arithmetic number, because the mean of its divisors is an integer number (1479940).

Almost surely, 2^66664400 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 66664400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88796400).

66664400 is an abundant number, since it is smaller than the sum of its proper divisors (110928400).

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

66664400 is a wasteful number, since it uses less digits than its factorization.

66664400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277 (or 266 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 32.

The square root of 66664400 is about 8164.8270036786. The cubic root of 66664400 is about 405.4755375446.

It can be divided in two parts, 66 and 664400, that added together give a palindrome (664466).

The spelling of 66664400 in words is "sixty-six million, six hundred sixty-four thousand, four hundred".