66905569 has 4 divisors (see below), whose sum is σ = 66951360. Its totient is φ = 66859780.

The previous prime is 66905567. The next prime is 66905603. The reversal of 66905569 is 96550966.

It is a happy number.

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: 96550966 = 2 ⋅48275483.

It is a cyclic number.

It is not a de Polignac number, because 66905569 - 2¹ = 66905567 is a prime.

It is a super-2 number, since 2×66905569² = 8952710326427522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66905567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20629 + ... + 23650.

It is an arithmetic number, because the mean of its divisors is an integer number (16737840).

Almost surely, 2^66905569 is an apocalyptic number.

It is an amenable number.

66905569 is a deficient number, since it is larger than the sum of its proper divisors (45791).

66905569 is a wasteful number, since it uses less digits than its factorization.

66905569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45790.

The product of its (nonzero) digits is 437400, while the sum is 46.

The square root of 66905569 is about 8179.5824465556. The cubic root of 66905569 is about 405.9639063742.

It can be divided in two parts, 669055 and 69, that added together give a square (669124 = 818²).

The spelling of 66905569 in words is "sixty-six million, nine hundred five thousand, five hundred sixty-nine".