66400840 has 64 divisors (see below), whose sum is σ = 163944000. Its totient is φ = 24003840.

The previous prime is 66400813. The next prime is 66400849. The reversal of 66400840 is 4800466.

66400840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 66400799 and 66400808.

It is not an unprimeable number, because it can be changed into a prime (66400849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 100431 + ... + 101089.

It is an arithmetic number, because the mean of its divisors is an integer number (2561625).

Almost surely, 2^66400840 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 66400840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (81972000).

66400840 is an abundant number, since it is smaller than the sum of its proper divisors (97543160).

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

66400840 is a wasteful number, since it uses less digits than its factorization.

66400840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 910 (or 906 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 66400840 is about 8148.6710572952. The cubic root of 66400840 is about 404.9404779670.

The spelling of 66400840 in words is "sixty-six million, four hundred thousand, eight hundred forty".