66618399 has 8 divisors (see below), whose sum is σ = 90991152. Its totient is φ = 43328960.

The previous prime is 66618367. The next prime is 66618401. The reversal of 66618399 is 99381666.

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

It is a cyclic number.

It is not a de Polignac number, because 66618399 - 2⁵ = 66618367 is a prime.

It is a super-2 number, since 2×66618399² = 8876022170646402, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66618319) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 270684 + ... + 270929.

It is an arithmetic number, because the mean of its divisors is an integer number (11373894).

Almost surely, 2^66618399 is an apocalyptic number.

66618399 is a deficient number, since it is larger than the sum of its proper divisors (24372753).

66618399 is a wasteful number, since it uses less digits than its factorization.

66618399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 541657.

The product of its digits is 419904, while the sum is 48.

The square root of 66618399 is about 8162.0094952162. The cubic root of 66618399 is about 405.3822515124.

The spelling of 66618399 in words is "sixty-six million, six hundred eighteen thousand, three hundred ninety-nine".