66139440 has 40 divisors (see below), whose sum is σ = 205033008. Its totient is φ = 17637120.

The previous prime is 66139439. The next prime is 66139453. The reversal of 66139440 is 4493166.

66139440 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (40).

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 7 ways as a sum of consecutive naturals, for example, 137551 + ... + 138030.

Almost surely, 2^66139440 is an apocalyptic number.

66139440 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

66139440 is an abundant number, since it is smaller than the sum of its proper divisors (138893568).

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

66139440 is a wasteful number, since it uses less digits than its factorization.

66139440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 275597 (or 275591 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 33.

The square root of 66139440 is about 8132.6158153450. The cubic root of 66139440 is about 404.4084031358.

The spelling of 66139440 in words is "sixty-six million, one hundred thirty-nine thousand, four hundred forty".