66561386 has 4 divisors (see below), whose sum is σ = 99842082. Its totient is φ = 33280692.

The previous prime is 66561373. The next prime is 66561403. The reversal of 66561386 is 68316566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 68316566 = 2 ⋅34158283.

It can be written as a sum of positive squares in only one way, i.e., 66178225 + 383161 = 8135^2 + 619^2 .

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 16640345 + ... + 16640348.

Almost surely, 2^66561386 is an apocalyptic number.

66561386 is a deficient number, since it is larger than the sum of its proper divisors (33280696).

66561386 is a wasteful number, since it uses less digits than its factorization.

66561386 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33280695.

The product of its digits is 155520, while the sum is 41.

The square root of 66561386 is about 8158.5161641073. The cubic root of 66561386 is about 405.2665744872.

The spelling of 66561386 in words is "sixty-six million, five hundred sixty-one thousand, three hundred eighty-six".