66402440 has 64 divisors (see below), whose sum is σ = 161829360. Its totient is φ = 24376320.

The previous prime is 66402439. The next prime is 66402461. The reversal of 66402440 is 4420466.

66402440 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 8 ways, for example, as 4024036 + 62378404 = 2006^2 + 7898^2 .

It is a Harshad number since it is a multiple of its sum of digits (26).

It is an unprimeable number.

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, 143810 + ... + 144270.

Almost surely, 2^66402440 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 66402440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (80914680).

66402440 is an abundant number, since it is smaller than the sum of its proper divisors (95426920).

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

66402440 is a wasteful number, since it uses less digits than its factorization.

66402440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 762 (or 758 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 26.

The square root of 66402440 is about 8148.7692322215. The cubic root of 66402440 is about 404.9437304337.

The spelling of 66402440 in words is "sixty-six million, four hundred two thousand, four hundred forty".