66809471 has 4 divisors (see below), whose sum is σ = 66832200. Its totient is φ = 66786744.

The previous prime is 66809461. The next prime is 66809489. The reversal of 66809471 is 17490866.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66809471 is a prime.

It is a super-3 number, since 3×66809471³ (a number of 24 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66809461) 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, 6161 + ... + 13098.

It is an arithmetic number, because the mean of its divisors is an integer number (16708050).

Almost surely, 2^66809471 is an apocalyptic number.

66809471 is a deficient number, since it is larger than the sum of its proper divisors (22729).

66809471 is a wasteful number, since it uses less digits than its factorization.

66809471 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22728.

The product of its (nonzero) digits is 72576, while the sum is 41.

The square root of 66809471 is about 8173.7060749699. The cubic root of 66809471 is about 405.7694481596.

The spelling of 66809471 in words is "sixty-six million, eight hundred nine thousand, four hundred seventy-one".