66209537 has 4 divisors (see below), whose sum is σ = 66247680. Its totient is φ = 66171396.

The previous prime is 66209519. The next prime is 66209557. The reversal of 66209537 is 73590266.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 73590266 = 2 ⋅36795133.

It is a cyclic number.

It is not a de Polignac number, because 66209537 - 2²⁰ = 65160961 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66209537.

It is not an unprimeable number, because it can be changed into a prime (66209557) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16337 + ... + 19982.

It is an arithmetic number, because the mean of its divisors is an integer number (16561920).

Almost surely, 2^66209537 is an apocalyptic number.

It is an amenable number.

66209537 is a deficient number, since it is larger than the sum of its proper divisors (38143).

66209537 is a wasteful number, since it uses less digits than its factorization.

66209537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38142.

The product of its (nonzero) digits is 68040, while the sum is 38.

The square root of 66209537 is about 8136.9242960716. The cubic root of 66209537 is about 404.5512216368.

The spelling of 66209537 in words is "sixty-six million, two hundred nine thousand, five hundred thirty-seven".