66641665 has 16 divisors (see below), whose sum is σ = 81772416. Its totient is φ = 52124800.

The previous prime is 66641657. The next prime is 66641671. The reversal of 66641665 is 56614666.

It is not a de Polignac number, because 66641665 - 2³ = 66641657 is a prime.

It is a super-2 number, since 2×66641665² = 8882223027944450, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45789 + ... + 47221.

It is an arithmetic number, because the mean of its divisors is an integer number (5110776).

Almost surely, 2^66641665 is an apocalyptic number.

It is an amenable number.

66641665 is a deficient number, since it is larger than the sum of its proper divisors (15130751).

66641665 is a wasteful number, since it uses less digits than its factorization.

66641665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1640.

The product of its digits is 155520, while the sum is 40.

The square root of 66641665 is about 8163.4346325551. The cubic root of 66641665 is about 405.4294383048.

The spelling of 66641665 in words is "sixty-six million, six hundred forty-one thousand, six hundred sixty-five".