66581361 has 48 divisors (see below), whose sum is σ = 124076160. Its totient is φ = 33384960.

The previous prime is 66581357. The next prime is 66581369. The reversal of 66581361 is 16318566.

It is a happy number.

It is not a de Polignac number, because 66581361 - 2² = 66581357 is a prime.

It is a super-2 number, since 2×66581361² = 8866155265224642, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (66581369) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 18441 + ... + 21753.

It is an arithmetic number, because the mean of its divisors is an integer number (2584920).

Almost surely, 2^66581361 is an apocalyptic number.

It is an amenable number.

66581361 is a deficient number, since it is larger than the sum of its proper divisors (57494799).

66581361 is a wasteful number, since it uses less digits than its factorization.

66581361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3366 (or 3363 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 66581361 is about 8159.7402532188. The cubic root of 66581361 is about 405.3071104528.

The spelling of 66581361 in words is "sixty-six million, five hundred eighty-one thousand, three hundred sixty-one".