66541509 has 12 divisors (see below), whose sum is σ = 96673356. Its totient is φ = 44103552.

The previous prime is 66541499. The next prime is 66541513. The reversal of 66541509 is 90514566.

66541509 is a `hidden beast` number, since 66 + 541 + 50 + 9 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 55130625 + 11410884 = 7425^2 + 3378^2 .

It is not a de Polignac number, because 66541509 - 2⁴ = 66541493 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66541549) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19812 + ... + 22925.

It is an arithmetic number, because the mean of its divisors is an integer number (8056113).

Almost surely, 2^66541509 is an apocalyptic number.

It is an amenable number.

66541509 is a deficient number, since it is larger than the sum of its proper divisors (30131847).

66541509 is a wasteful number, since it uses less digits than its factorization.

66541509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42916 (or 42913 counting only the distinct ones).

The product of its (nonzero) digits is 32400, while the sum is 36.

The square root of 66541509 is about 8157.2978982013. The cubic root of 66541509 is about 405.2262293453.

The spelling of 66541509 in words is "sixty-six million, five hundred forty-one thousand, five hundred nine".