66551818 has 8 divisors (see below), whose sum is σ = 99871812. Its totient is φ = 33261216.

The previous prime is 66551809. The next prime is 66551819. The reversal of 66551818 is 81815566.

It can be written as a sum of positive squares in 2 ways, for example, as 52316289 + 14235529 = 7233^2 + 3773^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (66551819) 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, 355 + ... + 11542.

Almost surely, 2^66551818 is an apocalyptic number.

66551818 is a deficient number, since it is larger than the sum of its proper divisors (33319994).

66551818 is a wasteful number, since it uses less digits than its factorization.

66551818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14696.

The product of its digits is 57600, while the sum is 40.

The square root of 66551818 is about 8157.9297618943. The cubic root of 66551818 is about 405.2471549376.

The spelling of 66551818 in words is "sixty-six million, five hundred fifty-one thousand, eight hundred eighteen".