66638140 has 24 divisors (see below), whose sum is σ = 142314480. Its totient is φ = 26203008.

The previous prime is 66638137. The next prime is 66638141. The reversal of 66638140 is 4183666.

It is a junction number, because it is equal to n+sod(n) for n = 66638096 and 66638105.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66638141) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 27057 + ... + 29416.

It is an arithmetic number, because the mean of its divisors is an integer number (5929770).

Almost surely, 2^66638140 is an apocalyptic number.

It is an amenable number.

66638140 is an abundant number, since it is smaller than the sum of its proper divisors (75676340).

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

66638140 is a wasteful number, since it uses less digits than its factorization.

66638140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56541 (or 56539 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 34.

The square root of 66638140 is about 8163.2187279283. The cubic root of 66638140 is about 405.4222898041.

The spelling of 66638140 in words is "sixty-six million, six hundred thirty-eight thousand, one hundred forty".