66990065 has 4 divisors (see below), whose sum is σ = 80388084. Its totient is φ = 53592048.

The previous prime is 66990061. The next prime is 66990071. The reversal of 66990065 is 56009966.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 56009966 = 2 ⋅28004983.

It can be written as a sum of positive squares in 2 ways, for example, as 26946481 + 40043584 = 5191^2 + 6328^2 .

It is a cyclic number.

It is not a de Polignac number, because 66990065 - 2² = 66990061 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66990061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6699002 + ... + 6699011.

It is an arithmetic number, because the mean of its divisors is an integer number (20097021).

Almost surely, 2^66990065 is an apocalyptic number.

It is an amenable number.

66990065 is a deficient number, since it is larger than the sum of its proper divisors (13398019).

66990065 is a wasteful number, since it uses less digits than its factorization.

66990065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13398018.

The product of its (nonzero) digits is 87480, while the sum is 41.

The square root of 66990065 is about 8184.7458726585. The cubic root of 66990065 is about 406.1347336888.

The spelling of 66990065 in words is "sixty-six million, nine hundred ninety thousand, sixty-five".