66440139 has 4 divisors (see below), whose sum is σ = 88586856. Its totient is φ = 44293424.

The previous prime is 66440137. The next prime is 66440173. The reversal of 66440139 is 93104466.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66440139 - 2¹ = 66440137 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66440137) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11073354 + ... + 11073359.

It is an arithmetic number, because the mean of its divisors is an integer number (22146714).

Almost surely, 2^66440139 is an apocalyptic number.

66440139 is a deficient number, since it is larger than the sum of its proper divisors (22146717).

66440139 is a wasteful number, since it uses less digits than its factorization.

66440139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22146716.

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

The square root of 66440139 is about 8151.0820754057. The cubic root of 66440139 is about 405.0203495338.

The spelling of 66440139 in words is "sixty-six million, four hundred forty thousand, one hundred thirty-nine".