6666400 has 72 divisors (see below), whose sum is σ = 17553564. Its totient is φ = 2457600.

The previous prime is 6666391. The next prime is 6666437. The reversal of 6666400 is 46666.

It can be written as a sum of positive squares in 6 ways, for example, as 2650384 + 4016016 = 1628^2 + 2004^2 .

It is an Ulam number.

It is a nialpdrome in base 10.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 10080 + ... + 10720.

Almost surely, 2^6666400 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 6666400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8776782).

6666400 is an abundant number, since it is smaller than the sum of its proper divisors (10887164).

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

6666400 is a wasteful number, since it uses less digits than its factorization.

6666400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 674 (or 661 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 6666400 is about 2581.9372571773. The cubic root of 6666400 is about 188.2046963133.

It can be divided in two parts, 66 and 66400, that added together give a palindrome (66466).

The spelling of 6666400 in words is "six million, six hundred sixty-six thousand, four hundred".