66540805 has 12 divisors (see below), whose sum is σ = 84824100. Its totient is φ = 50100224.

The previous prime is 66540791. The next prime is 66540821. The reversal of 66540805 is 50804566.

It can be written as a sum of positive squares in 6 ways, for example, as 833569 + 65707236 = 913^2 + 8106^2 .

It is not a de Polignac number, because 66540805 - 2⁹ = 66540293 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21580 + ... + 24469.

It is an arithmetic number, because the mean of its divisors is an integer number (7068675).

Almost surely, 2^66540805 is an apocalyptic number.

It is an amenable number.

66540805 is a deficient number, since it is larger than the sum of its proper divisors (18283295).

66540805 is a wasteful number, since it uses less digits than its factorization.

66540805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46088 (or 46071 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 34.

The square root of 66540805 is about 8157.2547465431. The cubic root of 66540805 is about 405.2248002610.

The spelling of 66540805 in words is "sixty-six million, five hundred forty thousand, eight hundred five".