66640015 has 8 divisors (see below), whose sum is σ = 86119488. Its totient is φ = 49211040.

The previous prime is 66640003. The next prime is 66640019. The reversal of 66640015 is 51004666.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 66640015 - 2²³ = 58251407 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66640019) 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, 512551 + ... + 512680.

It is an arithmetic number, because the mean of its divisors is an integer number (10764936).

Almost surely, 2^66640015 is an apocalyptic number.

66640015 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

66640015 is a deficient number, since it is larger than the sum of its proper divisors (19479473).

66640015 is a wasteful number, since it uses less digits than its factorization.

66640015 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1025249.

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 66640015 is about 8163.3335715258. Note that the first 3 decimals coincide. The cubic root of 66640015 is about 405.4260922295.

The spelling of 66640015 in words is "sixty-six million, six hundred forty thousand, fifteen".