66581447 has 4 divisors (see below), whose sum is σ = 66694320. Its totient is φ = 66468576.

The previous prime is 66581443. The next prime is 66581461. The reversal of 66581447 is 74418566.

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

It is a cyclic number.

It is not a de Polignac number, because 66581447 - 2² = 66581443 is a prime.

It is a super-2 number, since 2×66581447² = 8866178169227618, which contains 22 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 (66581443) 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, 55547 + ... + 56732.

It is an arithmetic number, because the mean of its divisors is an integer number (16673580).

Almost surely, 2^66581447 is an apocalyptic number.

66581447 is a deficient number, since it is larger than the sum of its proper divisors (112873).

66581447 is a wasteful number, since it uses less digits than its factorization.

66581447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112872.

The product of its digits is 161280, while the sum is 41.

The square root of 66581447 is about 8159.7455229927. The cubic root of 66581447 is about 405.3072849581.

The spelling of 66581447 in words is "sixty-six million, five hundred eighty-one thousand, four hundred forty-seven".